Just caught this article. Yea I have a amd machine. Seems sp3 will hose your machine if you have a amd chip.

 Windows XP Service Pack 3 finally arrived to our computers this week… And is now killing AMD machines, according to Jesper Johansson, former program manager for security policy at Microsoft.

The problem relates to machines with SP3 installed rebooting and then not allowing users to get so much as Safe Mode. The problem is mainly affecting AMD users who bought their machines from HP. Johansson attributes the problem to the way that HP puts images of Windows onto its machines, using the same copy for both Intel and AMD boxes.

"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," says Johansson.

Some other OEM’s beside HP have the same practice, and presumably their users will be seeing the same issue.

There is another problem with SP3 that has not yet been tracked down to anything so specific that is causing random hangs and system crashes, though at least one can get into Windows itself (unlike the lucky AMD users.)

Windows service packs causing mayhem and havoc is not a new phenomenon – indeed, AMD machines got hit with a similar bug back in 2000 when any machine running over 350 MHz crashed and burned after a new service pack was released – and we may wait a few weeks for all of the kinks to get sorted out.