OS X Mountain Lion: If you see a blue screen at startup

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If you see a blue screen at startup

If you see a blank blue screen or a blue screen with a colored pinwheel when you try to start your computer, but starting up doesn’t progress, you may have a problem with damaged or incompatible startup items or software.

Note: To print these instructions, open the Help Viewer’s Action pop-up menu (looks like a gear) and choose Print.
  • If you are starting up from a DVD, it must be a disc that came with your computer or OS X retail package. Discs from other Mac models may not work with your computer.
  • Restart the computer in safe mode. If the computer successfully starts up in safe mode, choose Apple menu > Restart to see whether the computer will restart normally.

    Start up in safe mode

  • If you see the login window prompting you for a user name and password, but starting up doesn't progress, you may have incompatible login items.

    If you think you have incompatible login items

  • Repair your startup disk or disk permissions using Disk Utility.

    Repair a disk

  • Back up your disk and then reinstall OS X.

    Reinstall OS X

Last Modified: Sep 4, 2015
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