My computer has been freezing after about 20 to 30 minutes. After acting normally, any icon I click yields nothing. If I go to the desktop, clicking any icon will not open a program. If I hit control/alt/delete, I can't even get into the Task Manager. The only way I can reboot, is from control/alt/delete shutdown. I can't even do this from the Start button. Any ideas on what is causing this -- or is it time to format and start from scratch. BTW, I have XP Pro.