According to this exhaustive FAQ on OS X kernel panic, it seems there are 5 main causes to that:

  1. Directory
  2. Drivers and Preference Panels
  3. Widgets
  4. Data corruption
  5. Permissions
  6. RAM and motherboards

I find this FAQ very useful especially because of the fact its author didn’t forget any of them (for the moment), for example the famous OS 10.2.5 USB hub caused KP.

Read the FAQ here.

Posted in Apple Hardware, Mac OS X, Security & Maintenance