Before anyone whose clock is running slow rushes out to buy a new
battery, he should first take note of whether he is losing time
while the computer is running or while it's powered off. If it's
while powered off, the problem *is* very likely the battery. But
if it's while running (which seems to be the case here), it can
*not* be the battery.
If the clock loses time while running, try this:
Open a command prompt window (Start | Run | cmd) and enter the
following commands:
net stop w32time
w32tm /unregister
w32tm /register
net start w32time