I have a Gateway XP and it continually looses 2 hours, even after resetting.
This problem seems to happen quite often with Dell machines, but also
with others. Usually a steady rate of loss like 10 minutes in an hour.
It appears to result from a conflict with the BIOS over the interval
between 'timer interrupts'. Windows maintains the clock by counting
these, so if the interval is not the expected one, the rate is grossly
out in this manner.
Try these steps:
1. Start->Run cmd.exe
2. net stop w32time
3. w32tm.exe /unregister
4. w32tm.exe /register
5. net start w32time
(note spellings w32tm and w32time in different commands)