This is from another board:
1. Run regedit and go to HKey_Local_Machine \Software\Microsoft\WindowsNT\Current Version\WPAEvents ,
on the right double click on "oobetimer" and change at least one digit of this value to deactivate windows .
2. Choose run from start menu and type in this command : %systemroot%\system32\oobe\msoobe.exe /a to
get the activation screen and go to the second option which is activate by phone .
3. In the new screen choose the option to change product key, and type in the new product key.
4. Close that window, reboot your system and enter the command in step 2 for the second time to verify your activation , you should see
"windows is already activated".
