what are you using to sync?
Try analogx, they have a good utility
(are you saying using the Windows time service?)
YOu gotta watch.. you don't want to sync time with something like bangladesh. Sure it will return the right time.. but that doesn't include time to travel
and as Telexen said that could be a sign of bad cmos battery... but if you're syncing it.. I'd guess something is not working correctly.