Update: Microsoft fixing patch that can slow Windows XP

"Microsoft help is usually the very last step I consider. I'm just too overwhelmed by the size and complexity of Microsoft's operating system, Web site, organization, et cetera," wrote Offer P., a home PC user in Israel who was able to restore his system speed to normal after removing the patch.

Toulouse, commenting on the user reaction, said Microsoft's free 866-PC SAFETY (866-727-2338) help line for virus-related support is also open for calls from users in the U.S. and Canada on issues with security patches. Users outside the U.S. and Canada can find numbers on Microsoft's support Web site at http://support.microsoft.com/, he said.

"If anyone is having issues I really want them to call the number for support," Toulouse said. So far Microsoft has had hardly any support calls on this Windows XP performance issue, he said.

In updating its security bulletin, Microsoft acknowledged those problems, but said that customers running Windows XP Service Pack 1 should still consider applying the flawed patch as protection until a new version is released.

"Customers are encouraged to review this security bulletin ... [and] assess whether their particular environments demand that the patch should be applied immediately or whether their particular level of risk permits delaying deployment of the patch until it is revised and the performance problem corrected," the company said.

Customers who restrict access between different users on a computer should install this update, Microsoft said in the end-user version of its bulletin. If the PC is only used by a single user or no passwords or other measures are used to limit access to accounts on the computer, it is not important to install this update, according to the bulletin. The end-user bulletin can be viewed at http://www.microsoft.com/security/security_bulletins/ms03-013.asp.

In response to the performance issues, Microsoft has lowered the Windows Update ranking for the security patch so it does not automatically install on systems that have the auto-update feature enabled. Also, the Windows Update Web site no longer displays the patch as critical, but as recommended, according to a Microsoft spokesman who asked not to be named.

"These steps were taken to give customers the opportunity to evaluate the patch before installing it," the spokesman said.

Microsoft is actively involved in finding a solution to the performance problems, in addition to investigating how the faulty patch made it through Microsoft's patch review process, Toulouse said.

Microsoft said it will also publish a knowledge base article that describes what environmental factors produce slow downs when combined with the XP patch and what can be done to reduce the impact of the slow downs should they occur.

That article should be available within the next few days, according to Toulouse. He declined to estimate when an updated patch that resolves the performance issues will be available, however.