Not quite random but odd. The pc only reboots when surfing the web in IE or Firefox, or checking email in Thunderbird. I have swapped out the powersupply and motherboard, brand new hard drive and added a chassis fan. I have run a full viruscan with the latest virus defs that were available at the time, I also have run spybot and adaware. All other tasks, including games can be run without a problem. The only hardware that I haven't swapped out yet is the processor and the ram, though it seems odd to be hardware with the fact that the workstation can be run for days without a problem if websurfing and email aren't touched. Any Ideas?