From my experience this can be 3 things.
1. Bad usb ports. Usually when controller is broken or most commonly when front panel the plugs are not in right.
2. Bad hardware. The keyboard may be faulty, have you tried it in another machine?
3. Registry problem. I've had some keys cause hardware not be recognised properly before. Only in XP though, not saying it isn't possible in vista.
Come to think of it, this happened to me once when I had a bad stick of RAM, so it'd be worth a thorough memory test too.
EDIT: Maybe you have a specific problem with board compatibility like thevet has posted.