My domain controllers, and thus my member servers and workstations were having some serious time drift. I’ve seen +/- 30 minutes this week so far. I found a good article from Microsoft on how to enable a computer (including domain controllers) to sync to an external time source (http://support.microsoft.com/kb/816042). I’m running two instances of Server 2008 server core, so I used the remote registry functionality to set the registry keys for w32time and restarted. I’m syncing to north-america.pool.ntp.org (don’t forget the ,0×1 at the end of our peer list).
Since my domain controllers are virtual machines, I also setup one of my physical hosts to sync to an external source as a backup.