Hi, I am using Windows XP + SP2. Every few hours everything slows down and Task Manager shows almost 100% CPU usage. Most of it (more than 80%) is taken up by SYSTEM (not System Idle Process), and it cannot be stopped. When it happens, the computer cannot be turned off, unless I press the OFF button. I have Norton Antvirus ver. 11 and have run an updated version of Spybot. I also clean the registry with CCleaner and Glary Utilities. I tend to believe that the problem occurs only when Windows Internet Explorer is running. I have restored IE8 to IE6, but it didn't help. Does any one have a clue to what is happening? Thanks, Ben