Yup, I just ran across this myself. The computer on boot each morning would detect new hardware and proceed with attempting to locate drivers, etc. There was no "new" hardware on this computer.
Basically, I uninstalled the software that running the external device that was connected to the computer (in this instance, it was a label maker printer) and disconnected the device. I rebooted the computer and sure enough, it did not detect new hardware. I reinstalled the device (that was working fine pror to this) and tested, and printed fine. Shutdown and powered back on, and the problem was solved.
My suggestion to you is to check the external device drivers first (if any), and even if it appears the device is working... uninstall the driver, disconnect the device and reboot. See if the detect new hardware comes up again, and if not.... that's the one to work with.
Win2000 seems to be a bit sensitive with external devices. Drivers seem to get corrupt a bit more often.