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.

They can't offload their problems onto us, especially with a paying customer and it's an issue that we can't solve. The retailer sounds like they haven't done anything wrong, if you're sure it's a genuine copy. So you need to phone MS and be very persistent with them