Task Manager shows 100% CPU utilization, but nothing in process list does.
My friend has a machine in his teashop that I am attempting to troubleshoot, so far with minimal success. It is a WinXP, 500MB, 2.12GHz. Nothing spectacular by today's standards, but a reasonable piece of equipment.
In the last couple of months, it has started a behavior that I have so far been unable to repair. When the machine sits idle for a while, it suddenly jumps to 100% CPU usage for no apparent reason. It has WinAmp running almost constantly, playing background music in the teashop, and usually a browser open, which the owner plods around on the net when not busy with the shop. This all works well and when WinAmp is running, usage is around 3-5%, as one might expect.
But when the owner leaves the computer idle for some time, the usage suddenly jumps to 100%, to the point where WinAmp can't even keep up - the played sound stutters so badly it's unrecognizable as music. This continues for around ten seconds, then stops, then resumes fifteen to twenty seconds later, stops again, and so on. It only quits when someone moves the mouse or presses a key. This happens regardless of whether a browser is open or not, and I've tried all three of the biggies.
The process names window shows nothing using that much power, although the CPU utilization line is at 100%. And it's almost impossible to do any research into the problem, because as soon as I move the mouse, it stops. I have an anti-virus (NOD32), have checked for spyware, unloaded everything suspicious from the start-up configs and installed a load balancing tool called ProcTamer. Nothing has helped.
Can anyone suggest something to try?