What about the uninstall or Play button ? Are they active, or none ? Seems like almost all the files might not have been erased from your hard drive. Ok, just make a back up of the save games that you have, then delete them from My documents. Also, delete all the files from where you have installed the game, including the folder. If you have contenets copied rom the DVD to your hard drive, delete them too.
Insert the disk, and check if the problem is resolved.