20" Intel iMac won't boot

I restarted my Mac by holding down the power button on the back of the computer after it froze. It will no longer boot. Instead, there is a flashing folder with a question mark.
I have inserted my install disc and held the C button, but that only gets me to the installer. Once there, disk utility shows my internal hard drive but there are no partitions shown under it and there is no first aid option.
I have also attempted to hold the shift key while it attempts to boot, as I've heard this will run some common fixes but it doesn't ever appear to do anything at all.
If I could simply get some of my data off the drive I'd not mind reinstalling the operating system.
Is there any way to get in any sort of maintenance mode to attempt to get some of my data off the drive?
Does the lack of partitions and the option for first aid mean anything about the state of my hard drive?
Thank you in advance for any help.

Hi Dustin
First try Testing and Repairing your Startup volume:
This link for 10.4
http://docs.info.apple.com/article.html?path=DiskUtility/10.5/en/duh1018.html
This link for 10.5
http://docs.info.apple.com/article.html?path=Mac/10.5/en/8492.html
And then run the Apple Hardware Test:
http://support.apple.com/kb/HT1509
Dennis

Similar Messages

Intel iMac won't boot & Disk Utility error-can't verify disk

I posted earlier today that my 24" intel iMac (2.4Ghz Core 2 Duo) froze yesterday after a Safari crash. I had to shut it down with the power button. Since then it won't start up. Sometimes it starts, then shuts off. Other times it starts, then the little gear just spins. I've done the keyboard commands for RAM, the complete disconnect of power, then reconnect, and the Disk Uitility with the install disk. When I do Disk Utility to verify, it gives me a red-letter error that it cannot verify on both verification checks. I have also tried, via the install disk, to repair by using a Time Machine backup, but that utility has been spinning and spinning on my Time Machine for hours, and I cannot even click the "Continue" button because it is busy (checking the time machine?)
I am out of ideas as to how to move on from here. My AppleCare expired 2 months ago, so that's a problem. I've had no major issues before now, except for earlier this year when Mail wouldn't open for some reason. Anyway, I'm at my wits' end here. I NEED my Mac. I'm disabled and have no better source of entertainment or socializing. My hobbies are editing audio, video, & photos. Without my Mac, I'm just in the middle of the sea in a raft with no oars. Any helpful suggestions will obviously be much appreciated. Thanks.

Reinstall OS X without erasing the drive
Do the following:
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.

Intel iMac won't boot from disc or in safe mode - cannot repair disk

I have an early Intel iMac 20" (2GHz core duo) that generally works fine. I recently ran Onyx and it reported a startup disk error, suggesting I insert the install disk, hold 'c', and use disk utility to repair the disk.
NOTE: I have performed this operation successfully in the past and know how to do it.
On this occasion, the iMac simply booted up to the normal desktop each time after multiple attempts at booting from both the original OSX 10.4.4 install disc and the OSX 10.5.1 install disc (current os is 10.5.8).
I then attempted to start holding 'shift' to start in safe mode but again, repeated attempts all landed me on my normal desktop.
I then attempted to hold 'option' to be given the choice of startup disc but again was ignored and went straight to my normal desktop after multiple attempts.
Note that my iMac appears to be running fine otherwise. I was just trying to perform some routine maintenance and have run across this problem.
Any ideas? This mac will be 5 years old soon and I would like to keep it running for a while longer.

Hello Devoidarex
You'll want to use the Leopard Install DVD to Repair your Startup Volume and may want to try a USB keyboard if your using a wireless.
Another option is to insert the DVD and go to: System Preferences > Startup Disk > select the Install DVD > then Restart.
Dennis

Intel imac won't boot with usb powered hub attached

My intel imac has started to not boot with a powered (have tried a variety of them) attached. Just stops at the white screen. Also, after I attach the hubs (2, both powered) the computer got into spurts when it just kicks everything attached to the hubs off saying that something pulled too much power. At other times it is fine with the same set up. I've tried resetting the PRam but it didn't make any difference.
I see from other postings that this isn't too uncommon, but didn't see any fix.
Thanks

Can you determine if it is just one of the hubs? Resetting the PRAM probably didn't have anything to do with this problem but the SMC controls the power, try this reset:
SMC RESET
http://support.apple.com/kb/HT3964
Shut down the computer.
Unplug the computer's power cord and ALL peripherals.
Wait 15 seconds.
Attach the computers power cable.
Wait another 5 seconds and press the power button to turn on the computer.
The 5 second timing is important to a successful reset.

Intel iMac won't boot. Starting chime, then beeping. What's wrong with it?

I pressed the power button on my iMac to turn it on - I didn't hold the button down, it was just a normal press - and it made the normal start up chime when turned on, but after that it beeps twice, then after that it beeps three times every three seconds and won't start up. I pressed the power button and tried again, but still the same thing. I tried holding down the power button to power on to do whatever that does (I can't remember exactly). It makes the long beep sound, makes the start up chime, then the same thing. I'm not sure what to do. I've have some very important files and projects that I can't afford to lose... sigh Can someone tell me what to do?
Message was edited by: digitalhigh

I've just had a similar problem. My 24" Intel iMac was shutting off but itself. It will start fine and after a couple of minutes it will shut off, till I couldn't start it anymore. It even beeped 3 times a couple of times. Tried everything that was adviced, then I took it to the apple store and they told me the problem was the power supply from the computer, they replaced it and now it's working fine.

Intel iMac won't boot up, please help.

Yesterday I downloaded the iPhone 2.1 Software Update, I then lost two thirds of my contacts, I managed to get them back using the Sync System, I then downloaded the Security Update, which failed "Due to an error" and was "put in the Trash". My computer then crashed, I restarted it and now it won't boot up, it gets as far as the White Screen with the Apple Logo on it with the Spinning Bars "loading" icon underneath, it was like that for over an hour last night and I've tried again this morning and it's the same. has my hard drive gone or is there some less (I hope) final reason for this? Is there an equivalent to Windoze safe mode or similar?
Please help urgently.
Thank You

Try this qst... Safe Boot , (holding Shift key down at bootup), off the HD & use Disk Utility from there to Repair Permissions, reboot once more.
If that doesn't help, Could be many things, we should start with this...
"Try Disk Utility
1. Insert the Mac OS X Install disc that came with your computer, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk."
http://docs.info.apple.com/article.html?artnum=106214
Then Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it finishes.
The usual reason why updates fail or mess things up, or things don't load/run, is if Permissions are not fixed before & after every update, with a reboot... you may get a partial update when the installer finds it doesn't have Permissions to change one obscure little part of the OS, leaving you with a mix of OS versions.
Some people get away without Repairing Permissions for years, some for only days.
If Permissions are wrong before applying an update, you could get mixed OS versions, if Directory is the slightest messed up, who knows!
If many Permission are repaired, or any Directory errors are found, you may need to re-apply some the latest/biggest updates again, or even do an A&I if you have enough free disk space.
If we still don't have it, try without a Tiger Disk, but try fsck...
To use fsck, you must run it from the command line. Unlike using your mouse to open an application to do something, you'll need to type a text command at the prompt (#) to tell fsck what to do. The Terminal application (/Applications/Utilities) and single-user mode are two examples of command-line interfaces in which you can type such commands. To use fsck:
1. Start up your computer in single-user mode to reach the command line. Hold CMD+s keys down at bootup. Note: If necessary, perform a forced restart as described in the Emergency Troubleshooting Handbook that came with your computer. On desktop computers, you can do this by pressing the reset/interrupt button (if there is one) or holding down the power button for several seconds. On portable computers, simultaneously press the Command-Control-power keys. If your portable computer doesn't restart with this method, you may need to reset the Power Manager.
2. At the command-line prompt, type /sbin/fsck -fy
3. Press Return. fsck will go through five "phases" and then return information about your disk's use and fragmentation. Once it finishes, it'll display this message if no issue is found: ** The volume (nameofvolume) appears to be OK  If fsck found issues and has altered, repaired, or fixed anything, it will display this message: *** FILE SYSTEM WAS MODIFIED ***   Important: If this message appears, repeat the fsck command you typed in step 2 until fsck tells you that your volume appears to be OK (first-pass repairs may uncover additional issues, so this is a normal thing to do).
4. When fsck reports that your volume is OK, type reboot at the prompt and then press Return.
http://docs.info.apple.com/article.html?artnum=106214
Then Safe Boot , (holding Shift key down at bootup), off the HD & use Disk Utility from there to Repair Permissions, reboot once more.

Intel iMac won't boot up when iPod is plugged into USB port.

I have a 2.16 GHz Intel Core 2 Duo with 2 GB of RAM and 667 MHz DDR2 SDRAM. Purchased new from Apple in January 2007. Running Mac OS X 10.4.10. Purchased a new 80 GB video iPod (v1.2.1) from Best Buy in June. Computer stopped rebooting soon after. I began by deleting preferences of various kinds with no luck. I've reset the P RAM, the System Power Manager or whatever ya call it. I've even done an Archive Install of the Mac OS. Yet every time I try an' reboot with the iPod plugged into the USB port I get the start-up chime then the gray screen and that's it. No gray Apple, no log-in window. I shut it down, unplug the iPod and it starts right up. Please, I'm beggin' ya. I don't want to have to wipe the hard drive and start from scratch. Any suggestions?
Thanks....

ABStrange -- the apple tech believes that the iMAC is trying to boot from the iPOD which is causing the hanging. Interestingly, if you wipe the iPOD clean, it will work flawlessly. The minute you put one song back on the iPOD it will hang again. Hopefully on Monday or Tuesday I'll hear something back. I'll let you know what I find out. I did mention this thread on the forum to the apple tech. Hopefully they take this seriously. Maybe it is a serious enough flaw with our iPODs that will warrant a replacement?
BTW: I upgraded to Leopard yesterday and the problem still exists. Was kind of curious to see if that had any effect.

Intel iMac won't boot from HD

About a month ago, HD booted to Loading OS X, then froze at blue screen before showing logon screen. Returned under warranty, techie used external FW drive and DiskWarrior to repair and system restored to normal. Now have my own external drive with OS X and DiskWarrior.
Last week, installed Parallels. Spent some time with networking to old PC in order to make transition from PC to mac easier (GBs of file transfers). Around this time, 4 of my prefpane files somehow reverted to Power PC, not Intel versions and I couldn't change system preferences on sound, speech, sharing and another beginning with s. Performed an archive and install, all seemed to be working OK.
Last night, screen went black with white power sleep light on constantly. Could only shut down with 5-sec power button push. Attempts to boot from HD get as far as Loading OS X, then freezes at blue screen (why are they always blue?). Restarted holding down option key. Can boot from FW drive. Ran Disk Utility and DiskWarrior. After lots of "node" messages and catalogue this and directory that, DU now shows drive green and OK. However, on trying to boot again from HD, system hangs after "Loading OS X".
Have reset PRAM, used command-s to enter console and did the 2 commands listed there but still no joy. Gone to apple support, have removed and reinstalled RAM iaw their instructions. Have done the SMC thingy, all iaw Apple's instructions. The mac is only 4 month's old and I don't know if anything else can be done before I take it back. Any assistance anyone could give me would be gratefully received.
All the best
jj
PS. Also updated firmware yesterday (1.2?). All seemed to go OK iaw Apple's instructions.
Message was edited by: jumbojock

{quote:} Last night, screen went black with white power sleep light on constantly. Could only shut down with 5-sec power button push. Attempts to boot from HD get as far as Loading OS X, then freezes at blue screen (why are they always blue?). Restarted holding down option key. Can boot from FW drive. Ran Disk Utility and DiskWarrior. After lots of "node" messages and catalogue this and directory that, DU now shows drive green and OK. However, on trying to boot again from HD, system hangs after "Loading OS X".{quote}
To return back to the Internal after a "Startup Volume Repair" from an (External HD or Install Disk 1) restart again holding the Option key (for Startup Manager) and select the "Mac OS X 10.4.10 on Macintosh HD".
Also go to: "Apple / System Preferences / Startup Disk" and select Mac HD, then click the lock so the system will allways attempt to boot from the Internal HD on startup or restart instead of searching.

My Intel iMac won't boot!!!

I was recording a TV show with my Elgato EyeTV. It wasn't finished but I had to go out of the house so I just left it recording. When I came back my screensaver was stuck. Completely frozen. So of course I just decided to restart it. The Apple logo showed up and the spinning wheel started spinning, like it always does. But it didn't stop. The hard drive must have been full!
I saw [this thread|http://www.mac-forums.com/forums/os-x-operating-system/124471-hard-disk- full-mac-wont-boot-up-cannot-install-leopard.html] about someone that had the same problem. He was told that he should reinstall Leopard, which would wipe out all the data on the hard drive. I do not want that!! I've got some really valuable things there!
Another guy said that by connecting another computer to it with a FireWire and boot up while pressing "T" I would be able to manage the files in the other computer. I did that, connected via FireWire, pressed T on startup and the disk "Macintosh HD" showed up as an external FW drive. But it seems to me that I only have a very limited time to do anything! After that it just shows up in "Devices" but I cant do anything! Once I was quick enough and I moved to the trash my EyeTV recordings. So I went to the Trash and hit the "Empty" button. The progress bar "Emptying trash" came up, but it didn't move! I wasn't quick enough.
So, what? Will I really have to reinstall MacOSX? Could I maybe be able to take it to an Apple Store and let them take a look at it?

If you are not afraid of using terminal.app, then you can boot from the install DVD and use terminal
to remove some files using the "rm" command.
http://manuals.info.apple.com/enUS/Command_Line_Adminv10.5.pdf
If you do not have your install disks handy, you can boot into single user mode:
To start up in single-user mode:
Choose Apple menu > Restart, or press the power button if the computer is turned off.
Press Command-S as the computer starts up.
The computer screen is black with standard white text. You can now run the UNIX commands that you want.
/sbin/mount -uw / #mounts the boot volume#
rm /path/to/file #removes file#
example: rm /users/me/videofiles/bigfatvideofile.mov
#this will remove the "bigfatvideofile.mov" file#
Be careful with the rm command, if you are new to using it, I suggest you stay away
from using it with the -R (file hierarchy) switch and the wildcard "*".
Using those subcommands inadvertantly could quickly give you a lot more room than you bargained
for!
Oh, almost forgot, If using single user mode, "reboot" is the command to leave SUM when you are done.
Kj

IMac won't boot at first attempt

Hi
Recently I've been experiencing that my intel iMac won't boot at first attempt and I have to powerdown manually and then try again. Second time it boots just fine. It's usually in the morning (been shut off for the night), but not always. I've tried disc utility from the install dvd, have repaired permissions and reset the nvram and everything seems just fine. The thing is, this has happened after the 10.4.8 update as far as I can remember. Does anyone else see this or is it a coincidence and some other problem?
Any thoughts would be appreciated.
Best regards
Rico
intel iMac 20" Mac OS X (10.4.8)
intel iMac 20" Mac OS X (10.4.8)

Oups, sorry about that wrong quote - I've been reading to many discussions lately
I've done all sorts of things today and I'm kind of curious to what is going to happen tomorrow morning when I boot up the mac. To sum up, here's what I've been doing:
Installed 10.4.8 manually, downloaded from: http://www.apple.com/support/downloads/macosx1048updateintel.html Read somewhere that the stand alone installer might help.
I ran repair permissions right after and got this:
Permissions differ on ./usr/standalone/i386/boot.efi, should be -r-xr-xr-x , they are -r--r--r--
Owner and group corrected on ./usr/standalone/i386/boot.efi
Permissions corrected on ./usr/standalone/i386/boot.efi
The privileges have been verified or repaired on the selected volume
Ran repair permissions again to check - all was good
Enabled automatically login in the accounts menu in user prefs - someone suggested me to do this, but I'm not sure what that might do, but hey, I'll give it all a shot.
Changed resolution and then back again to highest possible. Apple suggests this when the problem occurs on the 17" iMac.
http://docs.info.apple.com/article.html?artnum=303870
Unplugged power cord for 30 secs and reset smu (G5 article/idea though)
http://docs.info.apple.com/article.html?artnum=301733
Used Onyx to delete the content of library > caches which I read somewhere could perhaps help.
I'll post again tomorrow morning, and hopefully with some positive news

Intel iMac will not boot past gray screen

Intel iMac will not boot past gray screen
my system:
new (month old) 24" intel imac, 2.8 ghz, 4 gb ram.
running: leopard (upgraded from tiger, which was pre-installed at purchase), installed 10.5.1 update right before this huge problem occurred.
install discs on-hand: two-disc tiget set, single leopard upgrade disc.
what led to this:
i wanted to install windows using bootcamp on a 50 gb partition.
at this point i was running leopard 10.5
i followed all bootcamp instructions, printing out the guide, as well. once i got into the windows setup, i was prompted to choose a partition to install windows. unlike the bootcamp guide, which showed three partitions, one clearly labeled "bootcamp", i saw only one partition. not wanting to risk writing over my mac partition, i quit the setup and rebooted the mac os. after some googling around, i looked for firmware updates (didn't need any), and then software updates. i decided to try updating to 10.5.1.
i then ran through boot camp again, deleting my previous windows partition, creating a new one, and moving forward as before. once again, i was only shown one partition to choose from in the windows setup. i exited the setup again to reboot through the mac os, but this time, i was only given a blank gray screen.
here's what i have tried so far:
booting from a CD, holding down the C or D keys: no response (in fact, i have to restart the computer holding down the mouse button to be able to eject the CD)
booting with option key held down: gray screen
booting with option key held down with external bootable firewire drive attached: the firewire drive appears as a boot icon, and i can click on it within a five second window, but then the screen freezes after that time period, and nothing changes
booting into target mode while attached to another mac: gray screen (no firewire icon, and drive never shows up on other mac)
resetting NVRAM: i'm able to hear the boot chimes, but no difference in performance. gray screen every time
Safe boot: nothing but a gray screen
Verbose mode: gray screen
Single user mode: gray screen
Single user mode with firewire drive attached: occasionally (not every time), i am able to get the white on black terminal to show up. from here, i'm able to run fsck, but it appears to only be checking the firewire drive. i have tried several times to boot from here, and once it took me to a blue screen with movable arrow cursor, but it never went beyond this.
is there anything else left to try before taking it to apple?
any help would be greatly appreciated.
thanks,
Casey Burns
Casey Burns Illustration and Design
http://CaseyBurns.com

I'd call Apple support at this point. You'll need
to put this issue on the record.
Call U.S. iPod and Mac technical support: 1-800-APL-CARE (1-800-275-2273)
The wait may be long for an agent to come on the line
so expect that and have some other stuff to do in the meantime.
If you have the applecare protection plan, I'd ask about "onsite"
service.
I like your work ! Good luck !
Slim
Message was edited by: slimpikkunz

My iMac won't boot. I only get a white screen. Won't open in safe mode or recovery mode. Any suggestions?

Hey, any help? My 24" iMac won't boot. I only get a white screen when turning on. It won't open in safe or recovery mode. Any suggestions?

If you can't boot from your installer DVD, then take it in for service.

IMac won't boot to OS 9, boots Panther fine

Bought an iMac G3/500/128MB/CD-RW off Ebay for super cheap (this is the Indigo 500 with 64MB base RAM). Loaded OS 10.3.3 with no probs, tested it out with no probs. (I know the 128MB RAM is less than recommended/required for Panther, the machine was supposed to have 256MB and the seller is sending that to me). Next step was to load OS 9.1 from the CD. The iMac won't boot from the OS 9.1 CD (It boots fine from the Panther CD). Also tried booting from a firewire CD drive, same result. The result is a folder with a question mark, then a folder with a smily face, repeated twice before it aborts the OS 9 boot and goes into Panther.
Repaired permissions, no luck, wiped Panther off the drive and tried booting to OS 9 with blank drive, and still no luck.
As stated above, the machine was supposed to have 256MB RAM, and it also has a 20GB HD when it was supposed to have a 30GB HD. I declined a new HD as the seller offered me $20 as an option (bringing the total shipped down to $69.00), but now I'm wondering if I should replace the HD with the 30GB he offered? I don't think it's an HD issue though and replacing it looks like more trouble than it's worth.
I'm not too bummed if I have to stick to Panther, I just have a few OS 9 apps that I'd like to have access to.
iMac G3/500/128/CD-RW Mac OS X (10.3.3)

Does the CD drive boot from the Panther installation disk? I'm wondering if the CD drive is faulty, and it's not a Mac OS 9 specific issue.
Also, in combination with that problem, the hard drive may have been partitioned without the Mac OS 9 drivers. If you haven't tried already, use Disk Utility to partition the drive. You can keep it at one partition, but be sure that the "Mac OS 9 Drivers Installed" check box is installed. [NOTE: partitioning will wipe the drive clean.]
Other than that, I don't have a clue...
If you can't boot directly from Mac OS 9, most "classic" apps will run fine under Mac OS X in the "Classic" environment. If that works, it's actually a better way to access to Mac OS 9 programs.

My iMac won't boot past grey screen and it didn't come with a os x disk

My iMac won't boot past grey screen with apple. I've tried booting in safemode but that didn't help and my iMac didn't come with a os x disk.

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
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.”
b. 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.
c. 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 either of the techniques in Steps 1b and 1c 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 you use a wireless keyboard, trackpad, or mouse, replace or recharge the batteries. The battery level shown in the Bluetooth menu item may not be accurate.
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, or if a firmware password is set, or if the startup volume is a Fusion Drive or 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 10. 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
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 10
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 11
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 12
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.

27" iMac won't boot from anything BUT the main drive

Hi all,
My lovely 27" iMac is in perfect working condition, but I thought I'd try to install a OS on a large SD card to see if I would gain any speed.
In the process of doing that (cause I never got that far) I discover that the iMac won't boot from the original install DVD. It simply spits out the DVD when I try to insert into the drive. I'v managed to make an image of the DVD (in a different mac) onto the SD card in order to try an boot from that. No luck. I've tried to insert a original install DVD from my Mac Pro into the iMac, which it reads fine and well, and when I tap the restart button it restarts, but stop with a white screen doing boot up.
If I try to hold down the option key during startup, the iMac WILL let me choose which OS to boot from, but if I choose anything else than the OS already installed it freezes.
I've even tried to boot my Mac Pro from the iMac install DVD - no problems.
I've even run a hardware test on the iMac - no problems.
I am running out of options fast! Please help a devoted Mac-friend.
Take care.
Peter

I WAS using the DVD that came with the machine, but I fear Apple may have sent me the wrong one?
In trying to solve the issues I'd tried other OS disc's (A Mac Pro install DVD and a OS X Leopard DVD) - but none of them would even boot, nor install of my iMac. I always end up with a white screen during boot up.
As I described, the original iMac install DVD would indeed boot my Mac Pro, do the disc seems ok?

20" Intel iMac won't boot

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