A former Microsoft security manager has published a tool designed to detect and fix PCs that may be susceptible to 'endless reboots' if updated to Windows XP Service Pack 3 (SP3).

Jesper Johansson, once a program manager for security policy at Microsoft and currently an MVP (Microsoft Most Valuable Professional) who works at Amazon.com, posted a link to the tool on his blog on Wednesday, beating his former employer and HP to the draw. Neither company has yet come up with a fix or patch for the week-long snafu.

Windows XP SP3 review

Johansson's small, 16K VBScript (Visual Basic Scripting Edition) file checks whether the PC is running a processor from AMD, and if so, examines the Windows registry to see if a device driver meant for Intel-based machines is set to load.

"If it is, it will offer you an option to disable it," said Johansson in an update to a blog post where he has been summarising reports of Windows XP SP3 problems and offering solutions.

Users can run the script from the command line to check multiple machines on a network, Johansson added. The command is:

removeIntelPPMonAMD.vbs ...

"The only caveat is that the tool will prompt you several times for each computer," Johansson added.

The free-of-charge VBScript file is available for download.

The tool is the latest in the week-long problem some users have encountered after upgrading Windows XP to the new service pack. Last week, just a day after Microsoft added XP SP3 to Windows Update, reports accumulated of 'endless reboots' crippling machines running AMD CPUs. Many of the users said that the out-of-control PCs were from HP.

According to users, Johansson and most recently, Microsoft itself, the problem can be traced to the disk image that HP used to factory-install Windows XP on AMD-based machines. HP, said everyone concerned, used an image created on an Intel-powered PC to install XP on AMD systems; Microsoft had advised computer makers against doing that as long ago as 2004.

Microsoft was not immediately available for comment on Johansson's detection tool, but traditionally the company has taken a dim view of unsanctioned, unofficial fixes to its software.