Installing Windows XP Service Pack 3 sends some PCs into an endless series of reboots, according to posts to a Microsoft support forum.
Jesper Johansson, a former program manager for security policy at Microsoft and a prominent Windows blogger, has worked with users to tentatively identify the problem as involving only machines using processors from Advanced Micro Devices.
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.