Incorrect size of hardisk reported in XP

I have an IBM Hardisk (IC35L040AVER07-0) It is suddenly reporting it’s size to be much smaller than the 40 0r 60 Gigs (i forgot which one)that it used to report. I just found and removed the VBS_HAPTIME A-1 virus, but I’m not sure if it’s related ornot. Also, I tried to defrag the disk a few weeks ago but disk errors were reported. I tried to fix them but couldn’t while running XP. I tried to use the scan next time xp loads with the fix option but that failed to fix it?
Help! I use a Dell precision 340, 2ghz P4, 256 mg RDRAM