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Kernel panics are often caused by one or more of the following issues.

• Defective or incompatible RAM often causes of kernel panics. Despite being a highly-reliable product, RAM can fail. Modern operating systems, like Mac OS X, are sensitive to RAM. Purchase additional RAM from either Apple or third parties who guarantee their RAM is compatible with Mac OS X, offer a liberal exchange policy, and provide a lifetime warranty should the RAM become defective or a later version of Mac OS X introduce incompatibilities.

• Incompatible, obsolete, or corrupted kernel extensions. If a third-party kernel extension or one of its dependencies is incompatible or obsolete with respect to the version of Mac OS X you are using, kernel panics may occur when the kernel executes such extensions. Likewise, if a kernel extension or one of its dependencies is corrupted, such as the result of hard disk corruption, kernel panics are likely to occur when the kernel attempts to load or execute such.

• Incompatible, obsolete, or corrupted drivers. Similar to kernel extensions, drivers for third-party hardware which are incompatible with the version of Mac OS X you are using, or which have become corrupted, will cause in kernel panics.

• Hard disk corruption, including bad sectors, directory corruption, and other hard-disk ills.

• Incorrect permissions on System-related files or folders.

• Insufficient RAM and available hard disk space.

• Improperly installed hardware or software.

• Defective hardware or software. Hardware failures, including a defective CPU, or programming errors can result in kernel panics.

• Incompatible hardware. While rare, this is generally the result of a third-party hardware vendor’s product failing to properly respond to the kernel or a kernel extension in an expected way.

Specific causes of kernel panics

• A Mac that is incompatible with Mac OS X or is missing the System folder. If you receive a No driver for this platform message along with a kernel panic:, then:

• Your Mac may be incompatible with Mac OS X.

• Your Mac’s System folder may be missing or damaged.

• See the AppleCare® Knowledge Base document “Mac OS X: ‘No Driver for this platform’ Message.”

• Outdated firmware. Firmware-related bugs have been known to cause kernel panics. Firmware updates for your Mac may not appear in Software Update. Check for updates to your Mac's firmware by searching Apple Downloads for firmware updates for your specific model of Mac. For example, if you have an iMac®, use the search criterion iMac firmware to search for iMac-related firmware updates. Download and install applicable firmware updates.

• To determine the current version of firmware installed on your Mac:

• Open System Profiler, located in the Macintosh HD > Applications > Utilities folder.

• In the Contents pane — the left pane of the System Profiler window — selectHardware.

• The Hardware Overview for your Mac appears in the right pane of the System Profiler window.

• Your Mac's current Boot ROM firmware version is shown in the Boot ROM Version field. The Boot ROM firmware loads the operating system when you start up your Mac.

• Intel®-based Macs have a second firmware element specified in theSMC Version field. The SMC is the System Management Controller, which is responsible for the computer's power-management functions. See also the AppleCare Knowledge Base document "EFI and SMC firmware updates for Intel-based Macs."

• Improperly installed or loose AirPort® or AirPort Extreme® card. The card may have been installed upside-down or become dislodged. Consult the manual that came with your Mac for instructions on properly installing the AirPort or AirPort Extreme card. If your manual isn't handy, you can download a copy from the "Apple Manuals" page.

• Incorrect version of AirPort software with an AirPort Extreme card. Running an incorrect version of AirPort software with an AirPort Extreme card will result in a kernel panic. See the AppleCare Knowledge Base document “AirPort Extreme: Computer Doesn’t Start After Installing Card.”

• Corrupted sleepimage file on Mac portable computers employing safe sleep.

• Corrupted Time Machine® backup disk or backing up a corrupted disk or corrupted files with Time Machine.

• Journaling-related kernel panic. If the panic log begins with:

• panic(cpu 0 caller 0x0nnnnnnn): jnl: transaction too big...

• where nnnnnnn is a number representing a memory address, then see our "Journal-related kernel panic under Tiger" FAQ.

• Other Mac OS X bugs. Search the AppleCare® Knowledge Base for "kernel panic"(including the quotes), specifying the following additional search criteria:

• Restrict by product
: Choose your version of Mac OS X.

• Restrict by document type
: Choose Troubleshooting.