I get a white screen at startup that turns to checkerboard pattern

My iMac Intel 2012 20" displays white screen at startup then the screen turns to a checkerboard pattern adn goes no futher.
Thanks

Similar Messages

TS1367 Hallo,I have an IMAC 21.5. which does not start.When i press the power button i hear only beep with an interval of 4-5 seconds.Some times when i take off the RAMS and put them again then get a white screen and shows that i have to insert a bootable

Hallo ,I have an IMAC 21.5. which does not start.When i press the power button i hear only beep with an interval of 4-5 seconds.Some times when i take off the RAMS and put them again then get a white screen and shows that i have to insert a bootable device.Then i bought OSX mountainlion on line and wrote it on a DVD and tried with a USB key board to start the DVD.But does not work.Please help me to get this imac work.
Thankyou in advance for your help.
Terrence

Hey terremo,
Thanks for the question. From the information you provided, it sounds like the iMac is successfully turning on, however video is not displayed. These symptoms can usually be isolated further by the troubleshooting steps in this article:
Apple computers: Troubleshooting issues with video on internal or external displays
http://support.apple.com/kb/HT1573
Thanks,
Matt M.

Can't get past white screen when laotop is turned on

How can I get my MacBook to boot, won't get past white screen. Battery is fine.

Welcome to Apple Support Communities.
Sounds like it could be a problem with the hard disk.
You can diagnose and perhaps repair the problem (if the hard disk still runs, but has errors) with these instructions:
http://support.apple.com/kb/ts1417
Just realized that you're running OS X 10.7 Lion
http://support.apple.com/kb/DL1433
and
http://www.apple.com/macosx/recovery/
Message was edited by: kostby

HT1553 I did the back up as instructed... Installed a larger hard drive and followed the restore instructions... Now I get a white screen with a folder icon and blinking question mark. When trying to set startup with new drive I get a bless tool error...

I did the back up as instructed... Installed a larger hard drive and followed the restore instructions... Now I get a white screen with a folder icon and blinking question mark. When trying to set startup with new drive I get a bless tool error... Help!!

If you have installed a new hard drive , you will need to have formatted it in Disk Utility correctly. This may explain your problem.
Boot into your 10.6 Install disk again at the top menubar > Utilities > select Disk utility and in there select your new hard drive, and select the tab Erase and choose to make the format as Mac OS Extended Journaled. When that is finished look in the main window to make sure that the partition map scheme says GUID Partition Table.
Now go to the Restore tab and reinstall from your backup.

G5 startup won't get past White Screen, fans blow loud.

I have a G5 single 1.8GHz (late 2005 model?) serial number YM439*QYT
It gets stuck on the White Screen at startup. A minute later the fans start to blow really loud and it just keeps doing that and does not boot up.
I was using a hard drive that was copied from the original drive. So I put the original drive in and it was fine for a day. Now the computer is doing the same thing at startup with the original drive, as explained above.
I reset PRAM & NVRAM, nothing.
I have two different video cards, that's not the issue.
I do not have the OS Install Disc as this computer was given to me as a gift.
Any suggestions? Thanks.
<Edited by Host>

OK, from http://www.chipmunk.nl/klantenservice/applemodel.html
here is your system description:
Serial number: YM439*QYT
Name: PowerMac G5 (Late 2004)
Group1: PowerMac
Group2: G5
Generation: 3
ModelCode: g5june04
CPU speed: 1.8GHz
Memory - number of slots: 4
When you say white screen, are you talking about the gray screen with the apple in the middle? Do you see the progress gear at all before it stalls? Have you done a safe boot to force the fsck operation? You can also do a verbose boot (hold down cmd-V combination at power up and watch for dumb terminal output with Unix messages similar to what you see in the system log). Verbose booting might give you more information about where the stall is actually occurring, if it is stalling after the point where the terminal display begins.
Lots of voodoo in these situations, because there are lots of individual failures that can cause the problem.

My MacBook Air will not turn on. I get a white screen with the apple logo and a spinning star that just does that for hours

My MacBook Air will not turn on. I get a white screen with the apple logo and a spinning star (search icon). It will spin for hours and never go away unless I power off.

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
To restart an unresponsive computer, press and hold the power button for a few seconds until the power shuts off, then release, wait a few more seconds, and press it again briefly.
Step 1
The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.
There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.
a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.
b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, start up from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.
c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
If the startup process stops at a blank gray screen with no Apple logo or spinning "daisy wheel," then the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.
Step 3
Sometimes a startup failure can be resolved by resetting the NVRAM.
Step 4
If a desktop Mac hangs at a plain gray screen with a movable cursor, the keyboard may not be recognized. Press and hold the button on the side of an Apple wireless keyboard to make it discoverable. If need be, replace or recharge the batteries. If you're using a USB keyboard connected to a hub, connect it to a built-in port.
Step 5
If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.
Step 6
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
Step 7
If you've started from an external storage device, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.
Start up in safe mode. Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you start up in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 11. If you ever have another problem with the drive, replace it immediately.
If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)
If the startup process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 8
Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.
Step 9
If the startup device is an aftermarket SSD, it may need a firmware update and/or a forced "garbage collection." Instructions for doing this with a Crucial-branded SSD were posted here. Some of those instructions may apply to other brands of SSD, but you should check with the vendor's tech support.
Step 10
Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 11
Do as in Step 9, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.
Step 12
This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's and some others (not current models.) Both desktop and portable Macs used to have such a battery. The logic-board battery, if there is one, is separate from the main battery of a portable. A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 13
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

HT2452 White screen at startup and stays?? How can I get past this?

White screen at startup and stays?? How can I get past this?

Safe Boot is perfoming a disk integrity check and repair process which may take a long time. Let it complete, though if the startup disk requires repair to begin with, it is likely already in a failed state.
If the Mac eventually starts, take that opportunity to back up your important data if you have not already done so. It may be your last.

HT3964 I am not able to reboot my Mac desktop. When I switch on the Mac, I get a white screen with the Apple logo and the little wheel below that goes round and round but the computer refuses to boot.

Hi, I am not able to reboot my Mac desktop.
When I switch on the Mac, I get a white screen with the Apple logo and the little rotating circle.
The system refuses to boot.
What can I do?
Marcus

We need to get you moved. This forum is for mini-tower Macs built between 1998 and 2005 and doesn;t get as much traffic ("eyeballs on the problem") as the forums for newer Macs.
Please do "About this Mac" from you Apple menu and tell us what that says for "processor" and Mac OS version. Looks like this:
or this for later Mac OS versions:
With that we can figure out which of the two iMac forums you need and get the Hosts to move your post.

After reading and resetting everything with Keyboard I still get blank white screen. The only way I can boot to Mavericks is unplug power cord, push and hold power button while plugging power cord in. Fans at full speed.

After reading and resetting everything with Keyboard I still get blank white screen on 2nd? page of boot. The only way I can boot to Mavericks is unplug power cord, push and hold power button while plugging power cord in. Fans run at full speed, machine boots then runs normal except the dvdrw will not . The mid 2011 IMAC had the same problem with LION. I changed hard drives, formatted, and installed a clean install of latest os x mavericks. Any help would be greatly appreciated.
EtreCheck version: 1.9.15 (52)
Report generated August 30, 2014 at 6:56:41 PM EDT
Hardware Information: ?
    iMac (21.5-inch, Mid 2011) (Verified)
    iMac - model: iMac12,1
    1 2.5 GHz Intel Core i5 CPU: 4 cores
    4 GB RAM
Video Information: ?
    AMD Radeon HD 6750M - VRAM: 512 MB
        iMac 1920 x 1080
System Software: ?
    OS X 10.9.4 (13E28) - Uptime: 0 days 0:16:53
Disk Information: ?
    ST3120026AS disk0 : (120.03 GB)
    S.M.A.R.T. Status: Verified
        EFI (disk0s1) <not mounted>: 209.7 MB
        Untitled (disk0s2) / [Startup]: 119.17 GB (87.12 GB free)
        Recovery HD (disk0s3) <not mounted>: 650 MB
    HL-DT-STDVDRW GA32N
USB Information: ?
    Apple Inc. FaceTime HD Camera (Built-in)
    CHICONY USB NetVista Full Width Keyboard
    Apple Inc. BRCM2046 Hub
        Apple Inc. Bluetooth USB Host Controller
    Apple Computer, Inc. IR Receiver
    Apple Internal Memory Card Reader
Thunderbolt Information: ?
    Apple Inc. thunderbolt_bus
Gatekeeper: ?
    Anywhere
Kernel Extensions: ?
    [loaded]    com.nvidia.CUDA (1.1.0) Support
    [loaded]    com.sophos.kext.sav (9.0.61 - SDK 10.7) Support
    [loaded]    com.sophos.nke.swi (9.0.53 - SDK 10.8) Support
Startup Items: ?
    CUDA: Path: /System/Library/StartupItems/CUDA
    FanControlDaemon: Path: /Library/StartupItems/FanControlDaemon
Launch Daemons: ?
    [loaded]    com.adobe.fpsaud.plist Support
    [running]    com.arcsoft.eservutil.plist Support
    [running]    com.bjango.istatmenusdaemon.plist Support
    [loaded]    com.oracle.java.Helper-Tool.plist Support
    [running]    com.sophos.autoupdate.plist Support
    [running]    com.sophos.configuration.plist Support
    [running]    com.sophos.intercheck.plist Support
    [running]    com.sophos.notification.plist Support
    [running]    com.sophos.scan.plist Support
    [running]    com.sophos.sxld.plist Support
    [running]    com.sophos.webd.plist Support
Launch Agents: ?
    [running]    com.arcsoft.esinter.plist Support
    [running]    com.bjango.istatmenusagent.plist Support
    [loaded]    com.nvidia.CUDASoftwareUpdate.plist Support
    [loaded]    com.oracle.java.Java-Updater.plist Support
    [running]    com.sophos.uiserver.plist Support
User Login Items: ?
    Macs Fan Control
    Firefox
Internet Plug-ins: ?
    FlashPlayer-10.6: Version: 14.0.0.176 - SDK 10.6 Support
    Flash Player: Version: 14.0.0.176 - SDK 10.6 Support
    QuickTime Plugin: Version: 7.7.3
    JavaAppletPlugin: Version: Java 7 Update 67 Check version
    Default Browser: Version: 537 - SDK 10.9
Audio Plug-ins: ?
    BluetoothAudioPlugIn: Version: 1.0 - SDK 10.9
    AirPlay: Version: 2.0 - SDK 10.9
    AppleAVBAudio: Version: 203.2 - SDK 10.9
    iSightAudio: Version: 7.7.3 - SDK 10.9
iTunes Plug-ins: ?
    Quartz Composer Visualizer: Version: 1.4 - SDK 10.9
3rd Party Preference Panes: ?
    CUDA Preferences Support
    Fan Control Support
    Flash Player Support
    Java Support
Time Machine: ?
    Time Machine not configured!
Top Processes by CPU: ?
         1%    WindowServer
         1%    fontd
         0%    firefox
         0%    SystemUIServer
         0%    SophosWebIntelligence
Top Processes by Memory: ?
    229 MB    firefox
    156 MB    SophosScanD
    152 MB    InterCheck
    131 MB    com.apple.IconServicesAgent
    115 MB    SophosAntiVirus
Virtual Memory Information: ?
    424 MB    Free RAM
    1.53 GB    Active RAM
    1.37 GB    Inactive RAM
    699 MB    Wired RAM
    1.26 GB    Page-ins
    0 B    Page-outs

I'd start by getting rid of the following software responsible for these extensions.
Kernel Extensions: ?
    [loaded]    com.nvidia.CUDA (1.1.0) Support
    [loaded]    com.sophos.kext.sav (9.0.61 - SDK 10.7) Support
    [loaded]    com.sophos.nke.swi (9.0.53 - SDK 10.8) Support
Startup Items: ?
    CUDA: Path: /System/Library/StartupItems/CUDA
    FanControlDaemon: Path: /Library/StartupItems/FanControlDaemon
Use the uninstaller provided with the Sophos software. You can uninstall CUDA via the preference pane. Be sure you remove the com.nvidia.CUDA extension which is located in the /System/Library/Extensions/ folder. Not sure if Fan Control has an uninstaller so you will have to do it manually:
Uninstalling Software: The Basics
Most OS X applications are completely self-contained "packages" that can be uninstalled by simply dragging the application to the Trash. Applications may create preference files that are stored in the /Home/Library/Preferences/ folder. Although they do nothing once you delete the associated application, they do take up some disk space. If you want you can look for them in the above location and delete them, too.
Some applications may install an uninstaller program that can be used to remove the application. In some cases the uninstaller may be part of the application's installer, and is invoked by clicking on a Customize button that will appear during the install process.
Some applications may install components in the /Home/Library/Applications Support/ folder. You can also check there to see if the application has created a folder. You can also delete the folder that's in the Applications Support folder. Again, they don't do anything but take up disk space once the application is trashed.
Some applications may install a startupitem or a Log In item. Startupitems are usually installed in the /Library/StartupItems/ folder and less often in the /Home/Library/StartupItems/ folder. Log In Items are set in the Accounts preferences. Open System Preferences, click on the Accounts icon, then click on the LogIn Items tab. Locate the item in the list for the application you want to remove and click on the "-" button to delete it from the list.
Some software use startup daemons or agents that are a new feature of the OS. Look for them in /Library/LaunchAgents/ and /Library/LaunchDaemons/ or in /Home/Library/LaunchAgents/.
If an application installs any other files the best way to track them down is to do a Finder search using the application name or the developer name as the search term. Unfortunately Spotlight will not look in certain folders by default. You can modify Spotlight's behavior or use a third-party search utility, EasyFind, instead.
Some applications install a receipt in the /Library/Receipts/ folder. Usually with the same name as the program or the developer. The item generally has a ".pkg" extension. Be sure you also delete this item as some programs use it to determine if it's already installed.
There are many utilities that can uninstall applications. Here is a selection:
    1. AppZapper
    2. AppDelete
    3. Automaton
    4. Hazel
    5. AppCleaner
    6. CleanApp
    7. iTrash
    8. Amnesia
    9. Uninstaller
10. Spring Cleaning
For more information visit The XLab FAQs and read the FAQ on removing software.
Be sure to remove your two Login Items. Finally do this:
Reinstall Lion, Mountain Lion, or Mavericks without erasing drive
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Repair
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported then click on the Repair Permissions button. When the process is completed, then quit DU and return to the main menu.
Reinstall Lion, Mountain Lion, or Mavericks
OS X Mavericks- Reinstall OS X
OS X Mountain Lion- Reinstall OS X
OS X Lion- Reinstall Mac OS X
     Note: You will need an active Internet connection. I suggest using Ethernet
                 if possible because it is three times faster than wireless.

White Screen during Startup

Everything was working fine on the Mac until about an hour ago when I tried to install software updates and then the screen fades and a message pops up saying the computer needs to be restarted by holding down the power button.
After doing that, the computer is now stuck on a blank white screen every time it is restarted. FYI, there is no external hard drive connected to the computer. Here's what I have tried thus far to troubleshoot:
Completely disconnect from the electrical outlet and restart.
Restart with the OSX Install disc in (also tried this holding down "c", both times just goes straight to white screen and won't do anything else)
Tried resetting PRAM (it made the second chime but still wont go past the white screen)
Restart in single-user mode and safe mode (still just stuck on the white screen)
Tried restarting with any USB cables disconnected
Tried restarting with the Ethernet cord disconnected while holding down the D key per the instructions in the "Everything Mac" book (only thing connected was the keyboard + mouse)
NONE of this has worked or caused any different result, it's still just showing a blank white screen.
Can anyone suggest another possible solution or cause for this problem?
Thanks!

My iMac is brand new, barely 2 months old. I've been getting the white screen quite often at startup. The only way I can get past it is to hold down power and reboot. One thing I've noticed... I'm pretty sure it only happens when I have external drives connected. If I shut down with my hard drives mounted and restart, I tend to get a white screen. If I disconnect them, startup is perfectly fine. I'd hate to have to disconnect Time Machine every time I power down, though. What a pain. Just installed Snow Leopard; perhaps it will fix this (though it did not, sadly, fix the missing "new mail" sound, so who knows)?

Cannot get into mac. I get a white screen and flashing file folder with question mark inside. What can I do?

2012/13 MacBook Pro froze up, so I did a hard shut down. Now, when I try to start up, it makes 3 unusual beeps, then I get a white screen. After a couple minutes, a flashing file folder with a question mark appears and remains. What is wrong and what can I do to fix it.

Three beeps usually means a RAM or RAM slots problem. The Question Mark means there is no bootable system found.
A flashing question mark or globe appears when you start your Mac
Question (?) Mark, Blinking Folder, or Gray Screen at Startup
These are related but not identical issues. Their causes are outlined in Intel-based Mac- Startup sequence and error codes, symbols. Solutions may be found in:
A flashing question mark or globe appears when you start your Mac
Mac OS X- Gray screen appears during startup
In most cases the problems may be caused by one or more of these:
a. Problem with the computer's PRAM - See Resetting your Mac's PRAM and NVRAM.
b. Boot drive's directory has been corrupted - Repair with Disk Utility.
c. Critical system files are damaged or deleted - Reinstall OS X.
d. The disk drive is physically non-functional - Replace the hard drive.
Note that the information I have provided is what Apple recommends, If other users suggest different solutions than found here, then be sure what they recommend does not impact on your warranty, if any, or ability to get continuing Apple service.
Please don't start removing drives or changing cables unless you know what you are doing and have exhausted other non-invasive alternatives outlined here. If you perform any work yourself that is unapproved by Apple, then you will void any warranty you may have and lose all further Apple Support.
Repair the Hard Drive and Permissions
Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
The main difference if you are using Lion or Mountain Lion is that you must first boot from the Recovery HD. Simply boot from the Recovery HD to perform the above.
Reinstall Snow Leopard Without Erasing The drive
1. Repair the Hard Drive and Permissions
Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
2. Reinstall Snow Leopard
If the drive is OK then quit DU and return to the installer. Proceed with reinstalling OS X. Note that the Snow Leopard installer will not erase your drive or disturb your files. After installing a fresh copy of OS X the installer will move your Home folder, third-party applications, support items, and network preferences into the newly installed system.
Download and install Mac OS X 10.6.8 Update Combo v1.1.
Reinstalling Lion/Mountain Lion Without Erasing The Drive
Boot to the Recovery HD: Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the main menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu.
Reinstall Lion/Mountain Lion: Select Reinstall Lion/Mountain Lion and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

My 13" macbook just stopped working. When you turn it on you get a white screen and hear a repetitive clicking sound on the left side. Is this the hard drive? Any suggestions on replacement drives?

My 13" macbook just stopped working. When you turn it on you get a white screen and hear a repetitive clicking sound on the left side. Is this the hard drive? Any suggestions on replacement drives?
Thanks

Put your install DVD into the optical drive (CD/DVD drive) and reboot. Be sure to either use the disc that came with your Mac, or, if you installed a later Mac OS X version from disc, use the newer disc. As soon as you hear the boot chime, hold down the "c" key on your keyboard (or the Option Key until the Install Disk shows up) until the apple shows up. That will force your MacBook to boot from the install DVD in the optical drive.
When it does start up, you'll see a panel asking you to choose your language. Choose your language and press the Return key on your keyboard once. It will then present you with an Installation window. Completely ignore this window and click on Utilities in the top menu and scroll down to Disk Utility and click it. When it comes up is your Hard Drive in the list on the left?
If it is, then click on the Mac OS partition of your hard drive in the left hand list. Then select the First Aid Tab and run Repair Disk. The Repair Disk button won't be available until you've clicked on the Mac OS partition on your hard drive. If that repairs any problems run it again until the green OK appears and then run Repair Permissions. After repairing use Startup Disk from the same menu to choose your hard drive for restarting from your hard drive.
If your hard drive isn’t recognized in Disk Utility then your hard drive is probably dead.

Keep getting a white screen then the computer restarts?? PLEASE HELP!

It seems like every time the computer starts to work too hard it just gets a white screen for a few seconds then it restarts.
This is on a Satellite P105 laptop.
I took it apart and cleaned all the dust out as someone suggested and it is still doing it. The fans are coming on and I also have it sitting on a cooling pad. I dont know what else to do?! Could the video card be damaged completely? Or could it be some other problem?

Try the display driver first.
Does it happen with Wordpad? Start, Proggrams, Accessories.
See if you can find a simple way to reproduce the problem. Then try booting up in safe mdoe and see if it happens. if it doesn't happen in safe mode, then it might be something that is loading in normal windows. From the run command, run msconfig, and in that remove the checkmarks from everything in the Startup tab. If you don't have the problem with that, then slowly add the checkmarks back in until you see which one causes the problem.
If safe mode still has the problem, then Startup Repair, or system roll back are worth a try.
Post back if something worked, or need more info, or you have more info.
Hope that helps.
PS - While it could be hardware, there is a good chance it isn't and I think it is worth the effort to go down this road first.
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Imac wont boot - i get a white screen with apple logo, and it loads to about 10%, then screen goes black

imac wont boot - i get a white screen with apple logo, and it loads to about 10%, then screen goes black

Hey there mtriest,
It sounds like you are unable to boot the iMac successfully as it keeps shutting down when you try to boot. I suggest the troubleshooting from the following article named:
Mac OS X: Gray screen appears during startup
http://support.apple.com/kb/ts2570
Disconnect, test peripheral devices and network cables
Note: "Peripheral devices" refers to external devices other than what came with your Mac, such as hard drives, printers, or hubs that you connect via a USB or FireWire cable.
Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
Disconnect all peripheral devices such as external hard drives or printers (leave only the display, a keyboard, and mouse connected).
Disconnect any Ethernet cables.
Start up your Mac.
If you can start up this way, one or more of your peripheral devices (or installed software related to the device) is probably causing the gray screen issue. Connect one device, then restart your Mac to test for the issue. Repeat the process until you locate the device at issue. Make sure the device is powered if it needs to be to operate correctly. Check with the manufacturer of the device for support or possible software driver or firmware updates that may be available for the device. Try a different cable with the device if possible (such as a different USB or FireWire cable).
Note: If you have multiple peripheral devices and the issue only occurs when they are all connected, but not when each device is the only peripheral connected, see the Additional Information section below.
If you are using a desktop Mac with a third-party keyboard and/or mouse device, and the issue still occurs, try starting up with an Apple keyboard and mouse connected instead. Try starting with no keyboard and mouse connected, then connect them after start up. Also, try a different USB port on your Mac.
If the gray screen issue persists with no devices connected, go to the next section (with the peripherals still disconnected).
Perform a Safe BootSimply performing a Safe Boot may resolve this issue.
Shut down your Mac. If necessary, hold your Mac's power button for several seconds to force it to power down.
Start your Mac, then immediately hold the Shift key. This performs a Safe Boot. Advanced tip: If you want to see the status of a Safe Boot as it progresses, you can hold Shift-Command-V during start up (instead of just Shift).
Note: A Safe Boot takes longer than a typical start up because it includes a disk check and other operations.
If your Mac starts up as expected, immediately try restarting.
If the Safe Boot does not work, or the restart after a successful Safe Boot does not work, go to the next section.
There is additional information in the article with further troubleshooting if needed.
Thank you for using Apple Support Communities.
Cheers,
Sterling

My macbook pro won't start up. I get the white screen and the grey apple icon   the spinning wheel......and it doesn't change !

My macbook pro won't start up. I get the white screen and the grey apple icon   the spinning wheel......and it doesn't change !

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
To restart an unresponsive computer, press and hold the power button for a few seconds until the power shuts off, then release, wait a few more seconds, and press it again briefly.
Step 1
The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.
There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.
a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.
b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, start up from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.
c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
If the startup process stops at a blank gray screen with no Apple logo or spinning "daisy wheel," then the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.
Step 3
Sometimes a startup failure can be resolved by resetting the NVRAM.
Step 4
If a desktop Mac hangs at a plain gray screen with a movable cursor, the keyboard may not be recognized. Press and hold the button on the side of an Apple wireless keyboard to make it discoverable. If need be, replace or recharge the batteries. If you're using a USB keyboard connected to a hub, connect it to a built-in port.
Step 5
If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.
Step 6
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
Step 7
If you've started from an external storage device, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.
Start up in safe mode. Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you start up in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 11. If you ever have another problem with the drive, replace it immediately.
If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)
If the startup process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 8
Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.
Step 9
If the startup device is an aftermarket SSD, it may need a firmware update and/or a forced "garbage collection." Instructions for doing this with a Crucial-branded SSD were posted here. Some of those instructions may apply to other brands of SSD, but you should check with the vendor's tech support.
Step 10
Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 11
Do as in Step 9, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.
Step 12
This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's and some others (not current models.) Both desktop and portable Macs used to have such a battery. The logic-board battery, if there is one, is separate from the main battery of a portable. A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 13
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

I get a white screen at startup that turns to checkerboard pattern

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