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OS X Lion: If “You need to restart your computer” appears

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If “You need to restart your computer” appears

The message “You need to restart your computer” indicates that an error known as a “kernel panic” occurred. The most likely cause is a software problem. A kernel panic can also be caused by damaged or incompatible hardware, including external devices attached to your computer.

Note: To print these instructions, open the Help Viewer’s Action pop-up menu (looks like a gear) and choose Print.
  • Restart your computer by choosing Apple menu > Restart. Most of the time the kernel panic is an isolated event that requires no further action.

    For recurring kernel panics, continue with the list of suggestions.

  • Restart the computer in safe mode. If the computer successfully starts up in safe mode, choose Apple menu > Software Update, and then download and install any updates available for your computer.

    Start up in safe mode

  • Uninstall any plug-ins or other enhancement software from manufacturers other than Apple. If you recently updated Mac OS X or an application, plug-ins and other software that worked in the past may no longer be compatible. Read the manufacturer’s documentation (including Read Me notes) to be sure the software is compatible with your version of Mac OS X.
  • Reset parameter random-access memory (PRAM).

    Reset your computer’s PRAM

    Apple Support article: Mac OS X: What’s stored in PRAM?

  • Repair your startup disk or your disk permissions, or both. To do so, start up from your Mac OS X installation disc and use Disk Utility.

    Repair a disk

  • Disconnect all USB and FireWire devices, except for the Apple keyboard and mouse. Remove hardware upgrades from other manufacturers, such as random–access memory (RAM) and Peripheral Component Interconnect cards. Then try restarting your computer.

    If this resolves the issue, reconnect one device at a time, restarting your computer after reconnecting each one, until you’ve determined which device is causing the problem.

  • Use Apple Hardware Test. If you just installed hardware, such as additional memory, Apple Hardware Test can tell you if itʼs incompatible, improperly installed, or defective. If you canʼt find Apple Hardware Test, take your computer to an Apple Authorized Service Provider.

    Use Apple Hardware Test

  • If the steps above don’t help, try reinstalling Mac OS X.

    Reinstall Mac OS X

    Note: If you moved or renamed a Mac OS X system file or folder, then you must reinstall Mac OS X. It won’t work to just replace the specific item.
Last Modified: Oct 31, 2013
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  • Last Modified: Oct 31, 2013
  • Article: PH4192
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