Hi

We had a problem almost the same - Looked at CPU affinity, network cards etc.

In the end I found it was because Priority Boost was enabled on the installation (it was already there and the server failing before I arrived.)

Once I set this to 0 the mysterious reboots ended - along with the event viewer errors which used to happen 2 or 3 times a day.

Priority Boost changes require a service restart before they take affect.

Hope this help some of you

Seth

(actually just noticed someone else has said the same thing a few posts earlier - I'll leave this for those like me who get forum thread blindness)