I can't get past the grey apple screen using mavericks

Question

I can't get past the grey apple screen trying to boot up with Mavericks. I had been using Mavericks for about a month (only had issues of freezing occasionally). I read in one of the posts here that I should try holding command R down when booting. I did now I just get a grey screen without the apple.  Any advise?
I have a Mac Mini

Answer 1

Hello ther cnickers,
It sounds like the initial install of Mavericks went ok, and you have been using it for a while, but now cannot boot to your desktop and are stuck at a gray screen with an Apple logo. I would recommend a couple of things here:
First, try performing a Safe Boot to see if that will load up for you. If so then leave Safe Boot and restart from the Apple menu to try and get to your deskop:
To start up into Safe Mode (to Safe Boot), follow these steps.
Be sure your Mac is shut down.
Press the power button.
Immediately after you hear the startup tone, hold the Shift key.
The Shift key should be held as soon as possible after the startup tone, but not before the tone.
Release the Shift key when you see the gray Apple logo and the progress indicator (looks like a spinning gear).
After the logo appears, you should see a progress bar during startup. This indicates that your computer is performing a directory check as part of Safe Mode.
To leave Safe Mode, restart your computer without holding any keys during startup.
From: Mac OS X: What is Safe Boot, Safe Mode?
http://support.apple.com/kb/ht1564
If that works fine, I would next also verify and repair your disk if needed.
Disk Utility 12.x: Repair a disk
http://support.apple.com/kb/PH5836
Print this help page so you can refer to it later. (You don’t have access to Disk Utility Help when you restart up your computer in the next step.)In the Disk Utility Help window, choose Print from the Action pop-up menu (looks like a gear).
Choose Apple menu > Restart. Hold down the Command (⌘) and R keys as your computer restarts.When you see a white screen with an Apple logo in the middle, you can release the keys.
Click Disk Utility, and then click Continue.
In the list at the left, select the item you want to repair. (Be sure to select an item that’s indented to the right in the list, not an item at the far left.)
Click First Aid.
If Disk Utility tells you the disk is about to fail, back it up and replace it. You can’t repair it.
Click Repair Disk.If Disk Utility reports that the disk appears to be OK or has been repaired, you’re done. Otherwise, you may need to do one of the following steps.
If Disk Utility reports “overlapped extent allocation” errors, two or more files occupy the same space on your disk, and at least one of them is likely to be corrupted. Check each file in the list of affected files. If you can replace a file or recreate it, delete it. If it contains information you need, open it and examine its data to make sure it hasn’t been corrupted. (Most of the files in the list have aliases in a DamagedFiles folder at the top level of your disk.)
If Disk Utility can’t repair your disk or it reports “The underlying task reported failure,” try to repair the disk or partition again. If that doesn’t work, back up as much of your data as possible, reformat the disk, reinstall Mac OS X, and then restore your backed-up data.If you continue to have problems with your disk, it may be physically damaged and need to be replaced.
Thank you for using Apple Support Communities.
Cheers,
Sterling