I've had this CD key for a while, but I haven't used it with Steam before.

If you're sure that you haven't used this key in Steam before, it must be in use by someone else. This can happen if somebody else has copied your CD key, or if a virus has stolen it from your computer.

At this point, your only option is to mail in your CD key and have us reset it.

• Tell me how to mail in my CD key.
• This didn't resolve my problem.