Note for preinstalled system. The key fix may only work for systems made before March 2005 unless you got a new key from Microsoft. See rant.html for more details. I would still try it if you are having activation and wga problem with a legally purchase system or box.
Go to HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Current Version\WPAEvents
In the right pane, right-click OOBETimer, and then click Modify.
Change at least one digit of first line value to deactivate Windows.
If your windows system is already deactivated still do the above.
Run %systemroot%\system32\oobe\msoobe.exe /a
Preinstalled xp system use the key on the back of the machine.
Others use the same key, that you used to install windows xp
If you been giving a new key by Microsoft use that key instead.
Click Yes, I want to telephone a customer service representative to activate Windows, and then click Next. Click Change Product key. Type the product key in the New key boxes, and then click Update. If another Screen pops up-Click Remind me latter.
Then type in the Run box.
%systemroot%\system32\oobe\msoobe.exe /a
Choose Activate over the internet.
Then Reboot.
