Gmod Crash?

Alright, so my Gmod 10 was working like last month when my friend came over. However, when I try to launch it from Steam now, A black Garry’s Mod window (not full screen) comes up for a split second and then disappears with no error message or anything. I don’t think I’ve changed anything since I played it last, and my hardware isn’t the problem since it was working last month. Any help?

Thanks.

I don’t know if it works, but try setting launch options to -dxlevel 8.
It works for me, but a glitches in the interface occurs.

-dxlevel 80 it should be.

-dxlevel 8 makes it DirectX Level 0.8.