If you're one of the folks whose AMD-based PCs constantly reboot after applying XP SP3, here's how you can recover.
When the system is first booting, press F8 to enter Windows' Safe Mode. Log into the Administrator acccount, click Start, Run, type cmd, and press Enter. When the command window opens, type the following command (don't forget the space after the equals sign, which is required):
sc config intelppm start= disabled
The problem is caused by the presence of Intel drivers on AMD-based systems. Follow the above steps only if you know your PC uses an AMD processor; doing so on an Intel-based machine could render the system unusable.
To determine which processor your system uses, open the Control Panel's System applet and click the General tab. (See Figure 1.)
Windows XP's System Control Panel applet
Figure 1. Open the System applet in Control Panel to verify the type of processor your PC uses.
If the processor listed in the window is "Intel," do not enter the command shown above. An Intel-based system that constantly reboots may be having an unrelated problem. It might be caused by conflicts with antivirus products, as described in my previous item, or something else entirely that no one has yet identified.
As I wrote in my May 22 column, there's no rush to install XP SP3. Wait until we know more about these kinds of conflicts.