I recently had a few problems with my PC, first the Hard Drive packed up and then the power supply. Anyway as an interim measure i re installed my licensed copy of windows 7 on an old sata i had dug out from the cupboard, this was fine but as it was only a 150 gig i decided to replace it with a much quieter and bigger 500 Gig SATA drive. The reinstallation went well until i was asked yet again for the product key, it now says my product key is invalid, how can that be, it's only been used on the same PC, i may have re -installed a few times on different drives but same PC so why suddenly does it refuse to accept?? Help anyone!!