Try changing the driver on the keyboard. Could be a driver problem and could be a keyboard problem. If you had access to another keyboard you could test that and see if it makes a difference.
Since this could also be an operating system issue, this is a good way to test it. If another keyboard works, try replacing it or the driver, before you mess with the operating system. If you can revert to a previous save point like you can in ME or XP, that is one option to take.