Increasing numbers of Windows XP users are reporting problems after installing Service Pack 3.

Bloggers and vnunet.com readers have reported blue screens of death and eternal reboot cycles, and the problems are causing increasing frustration.

"What a good idea, I thought, and spent quite a bit of time downloading and installing," wrote reader 'Mike Watson'.

"Two hours later, having despaired of getting my system back to where I could actually get some useful work done, I have uninstalled it and have no intention of trying again. I only hope that the routine updates work better."

'Manzana' commented: "I installed SP3 via automatic update. Restarted and got the BSOD. Haven't yet figured out why but the only way to get into Windows was to disable USB in the BIOS and then connect via LogMeIn, then do a system restore."

Feedback to vnunet.com was not all negative, however. Some users praised the update, saying that their machines were running much faster.

A Microsoft employee believes that he may have some of the answers to the SP3 problems.

Dr Jesper Johansson said in his blog that the problems seem to hit AMD systems. "There are many possible reasons why a computer may crash at boot time," he wrote.

"SP3 seems to introduce two that are related to AMD-based computers and, possibly, one or two more that appear to affect Intel-based computers.

"Which one it is impacts which workaround you use. At this point, the information is still trickling in."