I'm experiencing a problem where XP freezes completely for a fraction of a second, every second. The mouse doesn't update, music stops, video stops - and then suddenly resumes.
I can't see anything using any CPU in Task Manager, and I've tried shutting down every service I can identify. There's nothing obvious in the Event Viewer.
The CPU graph (at highest refresh rate) looks like this for one of the two CPUs:
The "CPU Usage" alternates between showing 2% and 25% (ie, one CPU 50% utilised).
There is no significant network traffic. I can't think of anything else that could be causing it. Ideas?
UPDATE The next day, it wasn't doing this. But by the end of the day (after several hours sitting idle) it had reappeared. So apparently related to the machine being on for a while.