ok so I go to a clients and their pc reboots every time they go to log in. I remove the MS patch that nerfs Norton and things work fine, it even works fine in safe mode. However PC still reboots now but at random. I thought ok maybe it's the system overheating... but the heat sink is only barely warm. I thought ok maybe a bad heat sensor coding so I update the bios and still get the issue. Mind you this all started last week he's not sure the exact day. Here's the kicker. I get a reboot if I'm starting windows, running linux off a cd or if I do a scan disk. I can run a motherboard/cpu/memory diagnostics tool and a stress test program for hours on end and no errors or reboots. Any ideas?