I purchased a brand new copy of Halo 2 Vista and it installed perfectly and runs perfectly except for the Product Key doesn't work. I would contact the seller, but there's nothing they can do. They sold me a factory sealed brand new copy of the game. I tried talking with Microsoft support and they sent me here. I'm not going to dare trying an illegal Key generator, that's why I made sure I purchased a brand new copy of Halo 2 Vista.