Microsoft has recently released Service Pack 3 for Windows XP. Fortunately, at this time it is not being automatically installed through Automatic Updates. If you visit Windows Update and get prompted to install Service Pack 3, there are are some things you may want to consider before installing it.

Do you have an HP Desktop with an AMD processor (HP may not be the only manufacturer that did this)?

If you do then there is a good chance that XP will fail to boot or will enter an endless cycle of rebooting if you install Service Pack 3. Fortunately, the fix is fairly easy to follow and can even be applied before installation of SP3 to prevent a problem.

HP and possibly others used the same installation image for AMD systems as they did for Intel systems despite a Microsoft Knowledge Base article that states that this is an unsupported configuration. This seems to only affect HP desktop machines and not laptops. The result is that on HP desktop machines with AMD processors, the Intel Power Management driver is set to start as well as the AMD Power Management driver. After installation of Service Pack 3 this results in STOP error 0x0000007e.

To prevent this error before installing SP3 go to the 'Start' Menu and choose 'Run' then type "sc config intelppm start= disabled" and press the 'Enter' key. Note: Only perform this step if you are sure that you have an AMD processor. If you have an Intel processor this step will cause your computer not to boot.

If your computer is continually rebooting and you cannot see the STOP error before it reboots then as soon as the black Windows XP screen appears press the 'F8' key and then select 'Disable automatic restart on system failure' from the 'Advanced Options' menu that appears.

If you are receiving STOP error 0x0000007e then boot into 'Safe Mode' (If you are not prompted with that option then follow the information above about pressing 'F8' to get to the 'Advanced Options' menu. Once you are in 'Safe Mode' go to the 'Start' Menu and choose 'Run' then type "sc config intelppm start= disabled" and press the 'Enter' key.

There have been some reports that this fix may cause Media Center to disable the playback of DRM enabled media. If that is the case there is a workaround provided here that may solve the problem.

Do you have an ASUS A8N32-SLI Deluxe motherboard with an AMD processor?

Again, you may find that your computer will not boot after installing SP3. In this case you will see STOP error 0x000000A5 and a message that your BIOS is not fully ACPI compliant. This problem seems to be related to using a USB mouse. If your mouse also has a PS/2 connector or if it came with an adaptor you can try plugging it into the PS/2 port and this may solve your problem. Another workaround that seems to work is to plug a USB flash drive in before booting. The problem is that after that you will always have to have a USB flash drive connected to boot.

Some problems have also been reported with certain ATI video drivers, but they have not been confirmed yet. If you install SP3 and find that your computer won't boot but you do not have one of the problems listed above then you still have a couple of options.

Try booting into 'VGA' mode, if your system will boot in 'VGA' mode but won't boot normally, then the problem is almost certainly a video driver. You can try replacing the video driver with a newer or older version of the the driver and see if that will solve your problem.

Follow these instructions from Microsoft to uninstall Service Pack 3 until a solution for your problem can be found.

Microsoft is offering free unlimited installation and compatibility support for Service Pack 3 until April 14, 2009. The phone number for support is (866) 234-6020.