Kernel Panics: MacOS 10.1 & 10.2
Here are two examples of kernel panics that are displayed in OS X 10.1 and 10.2.
When you get a kernel panic, you will have to do a forced restart.

An example of MacOS X 10.1’s Kernel Panic screen.
An example of MacOS X 10.2’s Kernel Panic screen. Note that this may be displayed when the computer just wants you to restart, after an installation was done – it doesn’t mean it has crashed.