Hello,
Have you tried starting the computer in Safe Mode with networking support by repeatedly tapping the F8 key when the computer boots up and then tried reactivating http://www.microsoft.com/ (Microsoft) http://www.microsoft.com/windows/ (Windows) http://www.microsoft.com/windowsxp/ (XP) Home Edition on your computer?
If that does not work, it is possible the operating system was not reinstalled correctly, in which case you may need to take it back to the computer repair shop and have them correctly reinstall the operating system on it.
Regards,
Aryeh Goretsky
>> Stay informed about: Reinstalled WinXP and Reactivation