mine reboots when: 1. memory chips are bad 2. memory slot goes bad 3. motherboard is getting ready to go bad...(after it is bad it is lights out) my experience is that poser just hangs up, freezes when it is confused....sometimes it is me that is confused, Poser is just taking more time than usual for its project...but I have not had poser shut the machine and re-boot before..that sounds like a hardware problem...