Here's the thing. When I first bought Civ4 it wouldn't install on my cpu because of some error. It was the last one at the store, and I couldn't wait, so I went to some website and paid the cost of the game and they let me download it onto my cpu. It's like a 1.5 gig file. Now, whenever I download the updates it says something about how Civ4 isn't installed on my computer. Any ideas?