Keyboard Stops Responding in X

[Kimball Larsen]

I've got a breezy Ubuntu box that has an odd keyboard problem:

When I first boot up the computer, it starts X.org automatically, and  
presents me with a login screen.  I can type my password and press  
enter.  It then logs into KDE, but no keystrokes from the keyboard  
are recognized anymore. :( I even tried to VNC to the computer, and  
keystrokes from my VNC client are similarly ignored.  Switching out  
of X via CTRL-ALT-F2, the keyboard works again.

Thoughts?

Thanks!

-- Kimball