If you’ve done an emergency repair, re-install or XP fix you may encounter an activation issue. This can also happen if you’ve upgraded your PC motherboard.
Sometimes the screen hangs or you need to change the CD-Key
Boot into safemode click start, run and type %systemroot%\system32\oobe\msoobe.exe /a
Reboot the PC, download and install Internet Explorer 8
You can now activate / change your CD-Key