Just a guess but Im betting that you have Norton Internet Security on your computer. I have just gone through a long and painful process of learning the hard way that Norton internet Security and XP service pack 2, don't work and play well together. Since then I have replaced the internet security program with another product, I won't advertise for them so you pick one. But since the change everything seems to be running, and starting, and shutting down, much better. I am not claiming that I am a expert or that this is the cure, but it worked for me. Good luck!