My system is rebooting whenever it feels like it. I don't know if it's hardware or software. I'm planning on opening up the unit and using compressed air to blow out any excess dust. Apart from that, does anyone have any other suggestions? Is there some type of diagnostic software that might pinpoint the problem? I have a Dell Dimension 2400 desktop, running windows XP. I've had the system for about two years and this problem only started about 2 weeks ago. THANKS!!