I doubt I have the receipt anymore, I got it from target some time ago. ( I don't do most of my game shopping there, don't worry.) I'm looking forward to the game, though. I liked the first one.
I doubt it is a virus problem. I've had to instal the Sims 2 several times, many of which have run into problems. It's something of a sketchy process. As suggested above, try creating a disk image.