Time Issue

Quite a boring one but I can’t figure out why all the clocks on our network are running 10 mins fast. We have Windows 2000 Servers and 2k/XP clients.

It’s a problem going back some while now, we have reset the clock on the DC running the Windows Time Service and all other machines synchronise with this. They all show the correct time for a few days but eventually go back to being 10 minutes fast and stay that way.

Any thoughts?