Keyboard and Mouse Locked

I am running Win XP Pro SP2 on a custom-built machine. Recently my PS2
keyboard & mouse are locked when I get into Windows.
It started when the keyboard/mouse would freeze when I tried to use the
keyboard. I tried uninstalling the HP Driver and re-booting. Windows found
new hardware and asked me to click to install, but now both the keyboard and
mouse were locked. When I reboot into Windows, I have no way to input
anything. I tried using another PS2 keyboard with the original mouse, and
with a different mouse. Same results all around; the keyboard/mouse are
still locked.
Here's the kicker: If I intercept the system when I re-boot and go into the
boot menu or set-up menu, the keyboard works fine. This tells me I lost the
hardware definition and/or keyboard driver in Windows. Is there any way to
recover the driver or definition via the C:/> Command line? Or do I have to
spend the money for a USB keyboard/mouse? Other computers my house have a
USB wireless keyboard/mouse, but I'm hesitant to try them. We had a bit of
touble getting them set-up.
Any suggestions would be very welcome.
--
Curt Marlatt
(Professor Curt)