» Mon May 28, 2012 6:04 pm
Aye, fraid that there's not much we could suggest when it comes to problems with registring the game. I would though recommend to start up support tickets with both Bethesda and Steam, just in case either company's support monkeys try to hot potatoe you towards the other company for a resolution. Ideally if its a legit key and it isn't working because its already registered they'll be able to figure out who is currently using that key and do what they have to do to sort you out.
You didn't buy this from some third party on Amazon did you? Buying software like that is ripe for trouble and prone to short-term thinking sellers that try to pull stunts like that. (use the key and then sell the software to someone else)