Crashes 20 sec. into playing demo in Gmod.

So every time I try and play a demo that I made, it will run for about twenty seconds and crash. It has happened to all the demos I have made and I was wondering if it could be a sound/ video card problem? Because I do get laggy audio whenever I am in game sometimes and I play in windowed mode to try and reduce this as much as possible.
Thanks for any tips you guys might have!

Does it only crash in demos? Never anywhere else?

Yeah it’s just demos.

I know demos have a few issues; just record using a program. There’s too much serverside stuff to rely on demos.

Alright thanks. Any particular programs you guys would recommend? Or is that another thread entirely?

Bandicam or Fraps are probably the two most used.

dxtory is good