I have built a new Server 2008 domain with two domain controllers. I have configured the PDC emulator to sync with several public time servers following the Microsoft article on how to do this. This worked fine, and the second DC appeared to sync up without issue, however, after an hour or two they both reverted backwards about 5 hours or so. We are in Central Time Zone. I suspect that for some reason they are reverting to GMT (though it would make more sense if they moved forward 5 hours). One server is physical and the other is a virtual server in a VMWare environment. The virtual server is the PDC emulator currently. There doesn't seem to be a logical explanation for the sudden time change...both servers are patched all the way up. I must be missing something silly and stupid.