Garry's Mod black screen on start up

When I start Garry’s Mod after it loads and goes to the main menu a black screen appears, I can hear the game in the background if I join a server through friends list. It only effects Garry’s Mod, Garry’s Mod 13 works fine. I have tried reinstalling Garry’s Mod, my graphics card drivers are up to date

Anyone know how to fix this issue?

Thanks in advance.

Edit: Please ignore, starting Garry’s Mod in windows mode fixed it.