YOu kinda answered your own question. lol
Because if so I was thinking about reformating and installing a fresh copy of XP. If not it's most likely the motherboard huh?
Yes, do a freash install for XP. I had the same problem (w/o having computer retsart on a older comp) and the fresh os fixed it.
If that doesnt work, the mobo might be just to old, and might need replacing. If so give me info and ill find a good cheap replacement.