Just in case it may be something else, did you load those keyboard drivers on the other system you tested? Have you tried changing USB ports?
Maybe try another keyboard to pin down any possible problems.
The Ease of Access center has some options for keyboards, like sticky keys and filter keys, you might check for those.
In control panel, there may be a setting in Keyboards for certain keys. Perhaps make sure your keyboard is being recognized as the correct type and no special keys relevant to your situation are assigned.
Oh, and if you have been using it for a while, make sure and turn it over and gently tap to remove any debris.