Gmod "crashes" but can still hear sound

OS: Windows 7 x64
CPU: Intel i5 2500k
GPU: AMD Radeon HD 7950

Issue: Sometimes, when playing GMod, while experiencing high FPS and no lag or anything like that, GMod will minimize OR go to a black screen. Then, I can still hear everything that goes on, heck I can even type stuff in the console and it works, but I can’t actually see anything. And in the case of it minimizing, GMod is just a small black bar at the top left of the screen.

The only thing going on is a small 6 player deathmatch.

EDIT: “Display driver AMD has stopped responding” when it does that.

EDIT2: It looks like this while playing:

Updated Graphics drivers?
Not running any other applications?
Checked background applications and seeing if they want attention?

Only things open were Chrome, Steam, and task manager… nothing else.

Also now it’s constantly crashing my entire PC with a grey screen! Even while doing nothing on it.