Windows 2000 full cpu load issue20 January 2006
Compaq Evo D510 SFF with Microsoft Windows 2000 was not working, investigation showed cpu maxed out - all in the System process. Process Explorer showed 100% cpu split between System and DPCs, which seemed to indicate a device driver problem. A bit of internet searching led me to try disabling the USB drivers, but in the end I only had to disable “Intel PCI to USB Enhanced Host Controller” in the Device Manager to fix the problem, leaving USB still working.
MS Knowledge base (similar issue)