UE4 locks up my computer

Using UE4 is freezing my computer and I have to reboot after it happens. Unfortunately, since it doesn’t actually crash, these freezes don’t generate a crash report. The first time it happened, I had a scene with just a small platform and a single static model. I was working on a post-process material, and applied this:

After I applied the effect, I minimized the material editor and experienced the first lock up. I then removed the file but it still happens. So I opened one of UE4’s demo project in a different version of UE4, and it still locks up.

I can’t use UE4 without it freezing my computer within 5 seconds requiring me to force a shut down of my computer to fix it. Since I don’t get crash reports from this, all I can show is my dxdiag file.

Never mind, I think the problem was that I shouldn’t work for more than 12 hours straight. Opened UE4 after leaving my computer off overnight, and did not freeze my computer.