Hello. I have a pc just to test some programs and games (flash and java), and unfortunately by mistake, I activated Windows 8 Core (XXXXX-........-CYQG3). Someone can help me ? I tried upgrade with the DVD (XXXXX-......-J8CK4) and showup the option "You already have Windows 8, but you can add other features." and after I get the error "This key does not work. Check it out and try again ..."