Windows XP remains a standard throughout much of the IT community, and remains popular among consumers as well.  Thus many consumers are pleased that Windows XP Service Pack 3 is back in action, after being pulled a week for a software fix.  The new service pack provides additional useful features, numerous bugfixes, and minor performance improvements.

Unfortunately some users are also finding that it provides their computer with an endless reboot loop.  First, to dispel a common misconception, the reboot itself has nothing to do with a problem with XP SP3.  Rather, the problem is during the boot, which results in a crash.  In the case of the crash, Windows XP behaves correctly -- it reboots the computer and asks the user if they want to boot into safe mode, defaulting to a normal boot if no option is selected.

Users are not happy about the developments.  Michael Faklis posting on the Windows XP discussion board, vents, "My external disks are having trouble starting up, which results in Windows not starting up.  After three attempts [to install XP SP3] with different configurations each time, System Restore was the only way to get me out of deep s**t."

The source of many of the problems has been traced to manufacturers, which takes a bit of heat off Microsoft.  Perhaps the single biggest problem appears to be caused by Hewlett Packard's configuration choices.  By default HP deploys the driver intelppm.sys on all their computers, including those with AMD processors.  The driver provides power-management, but only for Intel machines.  On AMD machines a second driver, amdk8.sys is also added, which performs the same functionality for AMD processors.

If your machine's HP part number ends in a 'z', you probably have an AMD processor.  Or you could just peek inside.  Either way, if you have an AMD machine, you will likely experience crashes when you install Windows XP SP3.  This is really not Microsoft's fault as HP is installing an unsupported configuration by adding both drivers.  To fix the problem, if you haven't added SP3 yet, just type "disable intelppm" in the command prompt or run "sc config intelppm start= disabled" if you already installed it and can only boot to safe mode.

Another problem seems to occurring on certain motherboards, which affects USB devices.  Users found a simple fix to this problem -- some report that by plugging in a USB storage device their computer will boot normally, but without the device attached it will crash.  For non-AMD/HP users, this remains an option if dealing with crashes.  Also some have found that switching the mouse from USB to PS/2 port (via the adapter to the round PS/2 port) fixes the problem, indicating it may be an issue with USB mouse drivers.

Additionally, users of AMD's Catalyst 8.4 drivers have also reported some crashes.  To see if the video driver is the issue, boot to VGA mode.  If it works, the video driver may be to blame.  One isolate report of an NVIDIA related crash also occurred, but it was unreported what driver was used.  Other miscellaneous crashes appear to be due to systems with multiple hard disks. 

A very helpful resource to deal with the problems is provided by Microsoft MVP in Windows Security, Jesper Johansson, who offers additional helpful details to these and other potential problems and their fixes on his blog.

As Johansson points out, the most extreme solution when none other can be found is simply to uninstall XP SP3.  To do this, refer to the Microsoft Knowledge Base article on the topic.

While Windows XP is receiving some bad press due to the crashes, again, it appears that most of the crashes are due to hardware issues stemming from unsupported configurations, and thus the blame fall largely to the PC manufacturers, and the makers of component drivers. Fortunately, the majority of the problems have easy fixes that do not even requiring uninstalling the Service Pack.

Similar problems occurred with Windows Vista SP1, though in that case the blame ended up resting with a Microsoft pre-install update.  It is fairly typical for a Service Pack to take some computers out of commission, particularly one for an OS with as large an operating base and as varied a hardware environment as Windows XP.  Nonetheless, such problems are serious concerns for users affected, and those potentially at risk.