Keyboard & mouse don't work when windows 2000 boots

Hello All
I have a Win 2K pro pc for some reason when it boots up I can't get the
mouse or keyboard to work. The mouse pointer doesn't display, the num lock
comes on, but i can't turn it off. I have tried different keyboards & mice,
didn't work. I took the HD out & placed it as a slave in another pc, scaned
it with SAV, AVG, spybot, ewido, trend micro & panda active scan, all found
items and removed them, but I get the same results when I replace it as a
boot drive. When I boot into the BIOS the KB & mouse work, and when I used
ERD commander to boot the pc the KB & mouse work, so it's got to be
something in the Windows install that is on the HD. I also noticed that when
I used a optical mouse the led lit up when booting, but when Win 2K got to
the CTRl ALT DEL login screen the mouse light turned off like the mouse was
Anyone know of a virus that behaves like this?
I wanted to do a repair install , but when I try to boot with the boot disk
I mad I get
"File \ntkrnlmp.exe could not be loaded the error code is 7", I canged the
ram in the pc, and set the BIOS to defaults like the suggestion stated to
get rid of this error, but it did not work.
Any ideas are greatly appreciated