Hard locks.
Reboots
Blue Screens
Trap Exceptions
Corrupt System file errors
and eventually...
the moniter wouldn't even come out of hibernation mode when I turned on the computer - I heard no familiar startup beep, and the light, rather than green, was a baleful yellow...
Thankfully, after
Repairing Windows XP
Running CHKDSK
Running System File Check
and finally finding the right CD Key
The computer seemed to work fine. For a few days. After that, it relapsed into its old problems, but much less frequently. But no longer... the freezes and crashes have returned full force, and my computer won't even bring the monitor out of Hibernation more than half the time I turn the power on, much less boot all the way up.
Help me, Geeks to Go Forum Staff! You are my only hope!