I had an incident where my caps lock key got reversed -- the light would be on when caps lock was off. A restart solved it....
If this persists after a restart, I'd try another keyboard (desktop -- swap it out; laptop -- connect USB kb). If that doesn't help, then there is an issue with how your Mac interprets the input rather than a problem with the input that your keyboard is sending.
BTW, remember that it is possible to manually re-map (a.k.a., "customize") your keyboard for pretty much anything -- so it is possible that some überjerk/übergeek (what would that be? übergerk? überjeek?) did this -- but I wouldn't suggest going down the über-tinfoil-hat path just yet....