While I do have pets, none were in my room during the time while it rebooted and there are no children in my house.
This is a recycled computer, it was my old gaming computer from about 5 years ago. It has an i5 4690k, 2x8gb of ram and a corsair CX450 psu.
Before I started using unraid, it was functioning as a windows/ubuntu computer for a couple of weeks, which had no problems.
I'm going to try and snap a picture of when it crashes because the most recent reboot showed that text does appear on screen when it does crash.