Our computer has been giving us trouble for the past 3 or 4 months. These problems happen with XP, ME, 2000, 98SE and 95... but started in XP. Computer would shut itself off after several hours, then needed to wait at least half an hour to turn it back on. Power light remains on, and fan still runs, but computer wont work, nothing on screen (keyboard lights stay on though). It also reboots itself at random. Now the computer runs anywhere from 15 minutes up til 3 hours before it shuts off. Obviously makes it very frustrating and unreliable. Hard because I use it for work as well as leisure. We have an optic mouse (Qware) that just today started freezing. I wonder if that is causing the trouble? We have replaced power cords for the pc, checked all internal wiring, gotten a new fan, its been in the shop twice to be tested. Still it continues shutting itself off and maddening us. Any suggestions/advice? p.s. Its not a virus, we have NAV 2001 and its up to date, do a complete system scan weekly. Have formatted, and things still continue happening.