PC frozen

I can not select anything on my PC or use Task Manager. I hit a link on the web and a webpage became stuck on my screen and I can not close the browser and when I try to select desktop icons I just get a "beep". I can move my cursor and I can open Start Menu but can not select anything. The Task Manager will not open. Starting in Safe Mode does not improve anything, I still can't select any applications or Task Manager. How do I fix this? Can I fix this in Safe Mode with Command Prompt? If I could Restore my PC I thought I might be able to fix this but I can not select System Restore. Can I access System Restore with a Command Prompt? Or do I have to reinstall Windows XP? I tried to use Repair Windows with the XP CD but I do not know how to use the Command Prompt.

I have Spybot, Avast and Spywareblaster updated but these could not stop whatever happened to my PC.