Hello, I have a problem. I installed windows XP on a machine that had already had xp on it. Since the computer had no recovery disk, I used my copy of win xp that I have. The only thing was, the product key to go with the other copy of win xp was used up. But, I figured I could use the key on the back of the xp machine. Everything installed fine, but, when I go to change the key to the one back of the machnie, it says that it is an "incorrect product key". Why would it be saying this? Everything is typed correctly, it just wont accept it. Any ideas?