So when I get on PERP for an hour at least my Gmod isn't responding then crashes. I don't know if it is because of the demos starting to record and saving. But I need help with fixing it.
Have you tried verifying the game cache? You could also try reinstalling the content by manually deleting it from the folder. Sometimes the content causes unusual problems.
Regardless of whether it can run it, stuff can still pop up and cause problems like directx, things running in the background, etc. PAYDAY 2 doesn't always launch if you launched WATCH_DOGS without restarting your pc in between. So crash logs are important.