There are several warnings in here saying "Don't let SP3 near your computer".
Some folks have no problems, and wonder what the fuss is about.
Others have been through the pain. I had the problem on one machine, and eventually got it back to SP2 and working OK. I then turned OFF all automatic updates, wherever they are, and on all my computers. The stuff where I'm interested in updates knows to tell me when there is one available, and I'll decide whether or not to install it.
Apple's pesky iTunes/ iPod updaters ignore the "don't do it" setting, but ZoneAlarm knows not to let them through so they fall at that hurdle.