Running Windows XP on a AMD dual core processor. Occasionally after booting, logging on, and letting things settle down, the Task Manager shows on the graph that one processor is over 90% busy. Yet when one looks at processes running, system idle is at running around 98%. On performance graphs, the CPU usage bar shows as red with tiny amount of green. Only one user is logged on.
It is as though there is a rogue task that task manager doesn't know about when showing the processes, but does know about when showing the performance graphs.
I have seen this several times. What I've done in the past is reboot the system, and the problem/anomaly was no longer present. A log-off / log-on did not get rid of the rogue usage.
I have not explored if the issue is triggered by a long delay from power-up to log-on.
System seems clean on anti-virus scans. Network activity is zero.
Any ideas as to what might be happening?