Perhaps you have a disk going bad
Go to a command prompt
start/run
cmd
and run the command
fsutil dirty query c:
Replace C: with the drive letter being checked.
If it reports dirty then xp has flagged it because it has detected a problem
with it.
Run this command immediately after the system starts, if its dirty then,
either chkdsk isn't fixing the problem, or xp is detecting a problem
straight away.
Check in the system event log for any disk or file system errors, especially
timeouts and crc errors.
start/run
eventvwr.msc
Click on system in left hand pane to select system event log.
If you know the manufacturer of the hard disk, it wouldn't be a bad idea, to
go to their website and download and run their disk diagnostic utility, all
manufacturers have them.
Disk corruptions may also be caused by other hardware problems particularly
memory, Does your system scan memory when it starts up, do you see a counter
wizzing by when you first power on the system ?
Paul