I have about 10 WinVista/Win7 PCs connected to a standard Windows Server 2008 box. In the last 2 weeks, I've had power losses. Each time, all the PCs that use the Windows Server for DNS get seriously buggered. They no longer get DNS lookups from the Server.
When I reconfigure the PCs to use an alternate DNS, they work fine. The Server uses itself for DNS, and its running fine. There are no DNS events in the Event Log. However, using an alternate DNS server really does mess up some domain authentication and some PCs cannot share printers.
The first time, after about a week, I reconfigured the PCs back to using the Server for DNS, and they started to authenticate properly again.