Windows 2003 CPU Spiking (Not what you think)

[Dakkon]

We are having a weird issue on our network with server 2003. The CPU spikes and drops every few min or so from 70-100% to 0-2%, but does not happen all the time. Here comes the interesting part, when the CPU spikes to 70%-100% the server responds perfectly fine. Everyone can connect and browse drives, however when the CPU drops to 0-2%, everyone that is connected to that server freezes until the server spikes again. None of the processes on the server are spiking and dropping either, which boggles me the most. VirusScan has been done, and network utilization is around 1-4% at all times, unless the cpu drops to 0%, in which case it drops to 0%. This issue is really bugging me, any ideas? theories? anything would be helpful!

[faulkner132]

Was this a clean install or an upgrade?
Also, what are the machine specs?

[Dakkon]

Dual Xeon 1GHz, with 1.5GB ram, was a clean install.

[Omletteboy]

Have you looked at task manager>processes tab (make sure you check "show processes from all users". When it spike, see what process is causing it. Through that you should be able to track down what's causing your server issue.