After windows updates an XP computer with SP3, the computer may go in a reboot loop. And XP loads fine in Safe Mode. This particular problem occurs on systems that have been prepared with SysPrep. The sysprep image was created on an Intel based computer, and then the sysprep image is deployed on a Non-Intel system such as an AMD Processor.
How to resolve the issue?
Follow these steps to resolve this issue with the computer not booting correctly after SP3 is installed.
1) Start your computer in Safe Mode.
2) Click on Start, Run, and type REGEDIT and press Enter.
This will open the Registry Editor.
3) Click the pluses(+) next to the following registry keys to navigate to the correct spot.
4) In the right hand column find the entry titled START and double-click on it
5) Change the number to 4 and click Ok
6) Close the Registry Editor
7) Shut down your computer and restartThis time the computer should restart normally and finish the installation of SP3.