There seems to be an issue with XP Service Pack 3 (which was just released) with AMD Processors.

The problem is this:
After SP3 has been installed, when the computer is rebooted, it bluescreens.

The fix for the problem is this:
Choose F8 as the computer is starting up, and boot into Safe Mode. Once there, open regedit (Start->Run->regedit) and navigate to the following key:

HKLM\System\CurrentControlSet\Services\intelppm

Find the “Start” key. The value should be a 1; change it to a 4.

Close the registry editor and restart your computer. Everything should work now!