I have a 2012 domain with Windows 7 clients. Suddenly one client is having trouble syncing the time - at startup one day it was about 3 hours off. The timezone was set correctly. I've tried running "net time /RTSDOMAIN:domain /SET" and it syncs the client time to the PDC's time immediately, but after a while the clock starts to slow down again. Over the course of an hour it will get several minutes behind. This seems to be the only client with the issue. It's not a new client, has been running correctly for more than a year, and I'm unaware of any changes that could have caused this.