In my 3 years of owning a Mac, I have NEVER had one crash! Today my iMac has crashed twice! I transparent grey screen comes up and says to hold the powerbutton to restart. Then Once I've rebooted it says that MacOSX quit unexpectedly and asks to send a report! There was some kind of update this morning, I want to say an Airport update? after I got that is when it crashed. Then again this afternoon! I'm getting the new OSX update now maybe this will fix whatever is wrong. Any Ideas on what happened?
The grey screen is the result of something called a
Kernel Panic. The
kernel is the very core of Mac OS X, much like the kernel of a seed. The kernel handles the nitty-gritty details of interacting with the computer's hardware. Accesses to the CPU, memory, disks, network cards, USB peripherals, etc are ultimately managed by the kernel. An unexepected error inside of the kernel (called an 'unhandled exception') means that the kernel or your computer is in an unstable state. So, everything halts and displays the grey screen telling you to hit the restart button and start all over. If the kernel didn't halt, its possible that serious data loss or even hardware damage could occur.
Because of the important nature of the kernel, its supposed to be as bug-free as possible. That can be a difficult prospect. The kernel is extendable through pieces of software called
Kernel Extensions. These extensions extend the kernel's ability to interact with new kinds of hardware or software protocols. All of these extensions are loaded into the kernel at startup. If a kernel extension has a bug in it, it can cause the entire kernel to fail triggering a kernel panic.
The most common cuases of kernel panics are:
Buggy Kernel Extensions - Extensions can come from Apple or any other 3rd party. Some of them are poorly written, and will cause kernel instability.
Memory Failure - The kernel manages access to all parts of real memory. If parts of memory fail or become corrupted, all kinds of unpredictable behavior can occur. Application crashes, Kernel panics, and even disk corruption are all possible symptoms of bad memory.
Disk Failure/Corruption - The kernel manages access to all connected disks. If a disk begins to fail, behave erratically, or contains key information that has been corrupted, the kernel may panic.
Other Hardware Failure - The kernel manages access to all the computer's hardware, and if a piece of hardware begins to fail and act erratically, it can trigger a kernel panic.
Buggy Peripherals - The kernel manages access to all the computer's peripherals like USB devices and Firewire devices. If a peripheral behaves erratically, the kernel can panic.
Troubleshooting a kernel panic can sometimes be easy, and it can sometimes be very difficult. Information about the state of your computer when the kernel panicked is stored in a file called
panic.log which is inside of the
Logs folder inside of the
Library folder at the top level of your startup disk. If the kernel failed while it was running code from a specific kernel extension, the name of that extension will be listed in the information stored in the panic.log file. If the kernel failed while running code inside of its core, this could indicate any number of hardware problems.
