What version of Windows and what type of license.
e.g. Windows 8 and OEM (came with the computer), Windows 8 and retail, Windows 7 and OEM (came with the computer), Windows 7 and Retail?
Press [Windows] and [ r ] and type in slui 4 and press enter. Phone Microsoft and they should be able to assist you with the product activation.
Can you obtain your BIOS embedded system locked preinstallation key using RW-Everything?
What happens when you do change key?