Installing Windows XP Service Pack 3 sends some PCs into an endless series of reboots, according to posts to a Microsoft support forum.  Messages from frustrated users began accumulating on the XP SP3 support newsgroup Wednesday, just a day after Microsoft released the update to the general public.  "I just installed Windows XP SP3 and after completing the processes and when the system reboots, the system cannot proceed to load the Windows," said a user labeled as "Olin" in a message that kicked off a long thread. "It just displays the flash screen of Windows then after it reboots again. Most users who left messages on the forum said that they were unable to boot into Windows Safe mode.

According to Johansson (a former program manager for security policy at Microsoft), there appears to be two separate issues. One affects only AMD-equipped PCs sold by Hewlett-Packard Co. "The problem is that HP, apparently along with other OEMs, deploys the same image to Intel-based computers that they do to AMD-based computers," said Johansson. "Because the image for both Intel and AMD is the same, all have the intelppm.sys driver installed and running. That driver provides power management on Intel-based computers. On an AMD-based computer, amdk8.sys provides the same functionality."  Running the intelppm.sys driver on an AMD-powered PC isn't normally an issue, but on the first reboot after a service pack installation, it causes "a big problem," Johansson said. The machine either fails to boot or crashes and immediately reboots.

The other problem, according to Johansson, also seems to affect only AMD machines, and involves an error message indicating trouble with the PC's BIOS. Johansson said that the ensuing recommendation to update the BIOS is "most likely not your problem," but said that the problem may be isolated to a specific motherboard. "Possibly, it is related to computers with the Asus A8N32-SLI Deluxe motherboard in them," he said.

Johansson also spelled out workarounds for both problems on his blog. The HP issue can be solved by disabling the intelppm.sys driver, while the second fix requires the user to plug in a USB flash drive before booting.

Microsoft has also warned users updating to Windows XP Service Pack 3 (SP3) that they won't be able to downgrade from Internet Explorer 7 to the older IE6 without uninstalling the service pack. The warning first appeared in a post Monday to a company blog written by the Internet Explorer development team. Microsoft released Windows XP SP3 to Windows Update as an optional download Tuesday.  "If you choose to install XP SP3, Internet Explorer 7 will remain on your system after the install is complete," said Jane Maliouta, an IE program manager, in the blog entry. "Your preferences will be retained. However, you will no longer be able to uninstall IE7. If you go to Control Panel, Add/Remove Programs, the Remove option will be grayed out."  The inability to downgrade to IE6 after installing XP SP3 was by design, said Maliouta, because the service pack includes newer versions of the old browser's files. If Microsoft had allowed users to revert back to the pre-SP3 version of IE6 -- the one saved on users' PCs when they upgraded to IE7, and what was used until now to back out of the newer browser -- Windows would have ended up in a "mixed file state," Maliouta said.