for what it's worth: i had the exact same problem on a asus cuv266 appollo pro board, chased the problem around for days reinstalled xp, still happened, updated the bios, same problem. checked everything with a ohms meter, the cmos battery showed weak, put a new one in, used the seagate tools did a full erase of the drive, installed xp yet again. works fine and has been for over 6 months. dont know which actually helped , the battery or the format, pretty sure there was no virus on the drive before i started, and all the files i backed up i reinstalled with no problems, all the same software and updates are back on it so.....a 3 dollar battery is atleast worth a shot.