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OS X Mountain Lion: If your computer stops or delays while starting up

If your computer stops or delays while starting up

If your computer freezes, displays a flashing question mark, or delays while starting up, you may need to select a startup disk or repair your hard disk.

  • If your computer starts up after a brief delay or displays a question mark while starting up, you may need to select a startup disk. Choose Apple menu > System Preferences, click Startup Disk, and select a disk.
  • If you see a white screen with the Apple logo and a progress bar, OS X is checking your hard disk. This check could take a few moments.
  • If you start up your computer and the Apple logo doesn’t appear, shut it down by holding down the power button for about 10 seconds. Then hold down the Option key and start up your computer again. Keep holding down the Option key until one or more disk icons appear on your screen. Then select one of the disks. After your computer starts up, choose Apple menu > System Preferences, click Startup Disk, and select a disk.
  • Disconnect all peripheral devices, including FireWire, USB, and Thunderbolt devices. Connect an Apple keyboard and mouse to a USB port. Do not use hubs or extension cords.

    If you can use your computer now, there may be a problem with one of the other devices. Try reconnecting the other devices, one by one, to your computer. When you find the device that causes the problem, review its documentation for further troubleshooting steps.

  • Uninstall all third-party hardware upgrades, such as random-access memory (RAM) modules, PCI cards, and ExpressCard/34 cards.

    If you can use your computer now, there may be a problem with one of the upgrades. Try reinstalling the upgrades, one by one, to your computer. When you find the upgrade that causes the problem, review its documentation for further troubleshooting steps, or contact the manufacturer.

Last Modified: Aug 8, 2013
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  • Last Modified: Aug 8, 2013
  • Article: PH10929
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