How to change your Product ID in Windows XP
If the product key used in your workstation installations matches the leaked keys above, you may need to change the key in order to install Windows XP service pack 1, and to make sure your environment is legal. You could completely re-install Windows XP Professional or you can try the method below. (Please backup your system before attempting this.) This workaround is only for the corporate editions of Windows XP Professional using a compromised or illegitimate key. Windows XP Home Edition and retail versions of XP Professional should not be affected by Service Pack 1. Although this procedure may still work on other versions of XP, we have only tested it on the corporate edition (volume license version) of Windows XP Professional.
To change the product ID
Backup your system state by clicking Start > Run > and typing ntbackup > Click the Advanced Mode button in the Backup Utility Wizard. >Click the Backup tab, then in Click to select the check box for any drive, folder, or file that you want to back up, select the System State
Run regedit
Browse to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\wpaevents
Double-click OOBETimer
Remove the 'ca' part from the value
Click OK and close regedit
Click Start > Run and type in: "%systemroot%\system32\oobe\msoobe.exe /a"
Choose the 2nd option (phone activation)
Click Change Product Key (at the bottom)
Enter a valid Corporate Product Key
Press Update and close the window
Restart your computer
Verify the change
After the workstation restarts, click Start > Run
Type in: "%systemroot%\system32\oobe\msoobe.exe /a"
Make sure the dialog box says 'your copy of windows is already activated'
If you performed the above steps incorrectly, or used an invalid key, your system may not be able to boot. Use the F8 key to boot to the last known good configuration and retry with a valid key
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