Here is the answer to your problem (let us know if it worked)
http://www.askvg.com/windows-x...ion-of-service-pack-3/
As we all know Microsoft has released the final version of Windows XP SP3 to public and its available via Automatic Updates, Windows Updates and Downloads Center.
Earlier we posted about it at following link:
Windows XP SP3 RTM Available on Windows Update, Automatic Update and Download Center
You can download the SP3 from the above mentioned link.
I have received a few mails mentioning a strange problem which occurs while installing SP3 in Windows XP. A few ppl told me that whenever they try to install SP3 in Windows XP, Windows shows following error message:
Service pack 3 setup cannot update a checked (debug) system with a free (retail) version of service pack 3, or vice versa.
The reason behind this problem is that the update package installs retail bits on retail builds and checked bits on checked builds. But you can spoof Windows updates in order to install retail bits on checked builds and vice versa.
If you are also facing the same problem, then follow these simple steps and your problem should be solved:
1. Open regedit and goto:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion
2. In right-side pane look for a String value "CurrentType". Change its value to Checked and if its already set to Checked, then set it to Free and click on OK.
3. Exit registry editor and try to install SP3 again. Now it should install without any problem