Hi Nuyuu,
This isn’t really Unreal Engine specific, but… I think it might be that your CPU is overheating and shutting down your computer as an emergency response.
It might be a good idea to open your computer case (or whoever owns it should) and makes sure there isn’t excess dust buildup in your CPU / GPU heatsync. If there is, take it outside on a dry day and use some compressed air to clean it out.
If dust isn’t your problem, I would download a program like hwinfo64 and monitor your CPU and GPU temperatures while you have a game open. If your temperatures seem fine, you should also checkout running memtest86, which will help make sure there are no problems with your RAM.
Hope some of that is helpful!