I got the same issue. Upgraded from XP 32bit, but 64bit DVD wouldn't run in Windows. Booted from DVD and did a custom clean install, everything installed fine, got to the Install Key screen and was told key was invalid. Punched it in several times, same result. MS Techs told me bc it was 10/21 and that's why the key wasn't working, tried again on 10/22 same result. Can't get to the desktop until this key is entered. I'm sending it back and going to go buy another copy at BB. Hopefully it will work unless someone has some other idea?