keyboard almost not working under X11

[Mikhail T.]

Hello!

After working fine for a month, a system I put together for a friend
developed a bizarre problem. The keyboard is /almost/ not working under
X11.

It is perfectly fine on the text console, but under X11 one needs to
push buttons for a while with force... The mouse is fine and logging in
remotely works too.

I tried to replace the keyboard, but the effect was the same.
Powercycling did not help either.

I would've suspected the PS2-connectors on the motherboard, but it is
working fine in the text console...

Any ideas? Thanks!

	-mi