Random Error

[Tech Guy]

Ok, first off this error seems to be random and is popping up whenever it wants, the error just started today when a couple things happened:

1) installed Ad-aware SE, uninstalled it and it still pops up.
2) Changed the FSB from 100 MHz to 166 MHz, had to change it back because it seems that he doesn't have a fan over his processor, so it's underclocked about 800 MHz.

Anyway, without further adou. The error that keeps appearing is:

"list index out of bounds (0)"

Also, their can be a lot of these opened at the same time.

The machine has WinXP SP2.
it's an AMD Athlon XP 2500+, not sure of the motherboard, 1 GB Ram, and that's all I really know.