Windows 2000 vs. hidclass.sys on boot

I know of a system that (of course) for no known reason has started booting to a windows 2000 blue scree startup error regarding the drivers\hidclass.sys is missing or somesuch. Research so far on this file relates it to win98 powermanagement architecture and especially USB.
Any clues why this would be choking on a win2k system? The problem is further complicated in that while I have administrative access via a windows logon, I don’t have the Administrator account password, so attempted access via the Recovery Console is fruitless.