Well, since you've apparently already checked the time zone setting, there are a few other things to look at that might be affecting time settings. First of all, you can check the time synchronization settings on the servers by going to the commandline and typing:
net time /querysntp
This will return the name of a server that has been specified as the time server for that machine, or it will say that the machine is not currently configured to use a specific SNTP server. If you get the response that the machine is not currently configured to use a specific SNTP server, then it will automatically synch with whichever of your DCs has the PDC Emulator role in your domain (usually this will be the first Win2K DC that you installed in the domain, unless you have changed it). The DC that has the PDC Emulator role should be synchronized with an outside SNTP server. You can easily do this if you have an Internet connection of any type by the following command on the PDC Emulator machine:
net time /setsntp:[servername or IP address]
If you are in the US, the Navy and NIST (National Institution of Standards and Technology) both have time servers you can use. You can go to their web sites to get info on how to use their SNTP servers. I use the NIST ones myself. Other countries I'm sure have similar services out there. The default settings will cause you server to check it's time setting twice a day.
Second of all, there might be some type of service running on these DCs that is resetting the time or causing the servers to lose time. Have you looked into that at all? Do you see any sort of event log message or can you identify anything else that seems to be happening when the time gets reset?
Hope this helps!
