I think it is being caused by your network, or at least that is my experience. My theory is the thing is locking-up from noise one the line causing a buffer to overflow... Pulling the network adapter would prove whether or not it is causing it.
One should take the time to calculate how much it costs to leave a computer on overnight. You might be surprised. I also consider it to be a fire hazard. Why? Because over the years I have seen more than one computer sitting in my showroom or shop fail with clouds of smoke. Of course, we did leave servers on and burn-in computers overnight. But we had smoke detectors, etc. on a monitored system wired to the police and fire departments. Larry