ghost CD detected upon startup

Whenever I restart my new MacBook Pro, it always tells me I have a CD in the drive, and it either asks me whether to ignore it, eject it, or format it, or it tells me it can't read it. Funny thing is, there IS no CD in the drive; in fact, I don't think there's ever been one, at least since it left the factory. Any advice on how to fix this annoying behavior?