Microsoft blames computer makers for some of the problems users have encountered after updating to Windows XP Service Pack 3 (SP3), according to a company support document.

The document also showed that the "endless reboot" problem some users have reported after installing XP SP3 was neither unanticipated or new; Microsoft updated the document the same day it released the service pack, and indicated that the same thing happened nearly four years ago when it rolled out Windows XP SP2.

Knowledge Base document 888372, last updated May 6, spelled out an error message that stops a PC's boot process -- and, depending on the machine's settings, may make it repeatedly reboot -- after installing SP3. The fault, said the Microsoft document, is in the Windows XP image originally installed on the PC by the computer manufacturer, or OEM.

"The problem may occur if the original Windows XP Service Pack 1 (SP1) Sysprep image is created on an Intel-processor-based computer and if the Sysprep image is then deployed on a non-Intel-processor-based computer," said Microsoft.

"Under this configuration, after the computer is upgraded to Windows XP SP2 or SP3, the Intel processor driver (Intelppm.sys) may try to load because an orphaned registry key remains from the original Sysprep image," the document continued. "This issue may also occur if the original Windows XP SP2 or Windows XP SP3 Sysprep image is created on an Intel-processor-based computer and if it is then deployed onto a non-Intel-processor-based computer. Again, the Intel processor driver (Intelppm.sys) may try to load because an orphaned registry key remains from the original Sysprep image."

A day after Microsoft added XP SP3 to Windows Update, users began reporting that their machines processors from Advanced Micro Devices (AMD) were rebooting endlessly. Many of them said that the crippled systems were from Hewlett-Packard.

"I too have an HP Pavilion with an AMD Athelon [sic] processor," said a user identified as "jrednasnh" in a message posted Saturday to a Microsoft support forum. "I find it discouraging that HP may be partially at fault and did not attempt to notify us AMD customers, nor attempt to fix the issue."

Jesper Johansson, a former program manager for security policy at Microsoft and currently an MVP (Microsoft Most Valuable Professional), worked with others to identify some of the reboot issues as involving PCs running AMD CPUs. Johansson, who said one of his HP PCs repeatedly rebooted after installing XP SP3, traded accounts with several other users on the newsgroup and summarized the results on his blog.

"The problem is that HP, and possibly other OEMs, deploy the same image to Intel-based desktops that they do to AMD-based desktops," Johansson said. "Microsoft points out in a Knowledge Base article that installing both drivers on the same computer is an unsupported configuration, putting the blame on the OEM that deploys the image. The article in question was written when the same problem occurred after installing Service Pack 2 for Windows XP." Microsoft unveiled XP SP2 in August 2004.

According to Johansson, only HP desktop models are affected. "It also appears that this is unique to their desktop image, and any HP AMD-based laptops are unaffected by the problem," he said.

As Johansson mentioned, Microsoft has dubbed the practice "unsupported" in KB888372. "We do not support using Sysprep to install an operating system from an image if the image was created by using a computer that has a different processor," said Microsoft. "For example, you cannot create a Sysprep image on a computer that has an Intel processor and deploy the image to a computer that has an AMD processor."

KB888372 instructed users how to modify the Windows registry to disable the errant Intel driver, assuming users could regain control of their PCs long enough to boot into Safe mode.

The company has also listed several other scenarios that OEMs should avoid in another support document.

Microsoft and Hewlett-Packard did not immediately respond to questions Sunday.

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