Gmod crashes and then shuts down PC when a Youtube Video is playing

Hi everyone, lately I have been experiencing some problems. Whenever a Youtube Video is being played (On a server, Web browser etc). My Gmod would crash and then Shut down my PC without any warnings.
When Gmod 13 went live, I didn’t have any of these problems. And then a few Updates later, I started to crash. I’ve asked lots of people and they don’t have the problem. Any suggestions on how to fix this?