Gmod wont load, even singleplayer

my gmod just suddently decided not to work, even after a complete reinstall of steam and gmod it still craches when you tell it to run single-player it craches at the loading screen. Also when you go to join a game the main menu dosnt disapear and then the server list dosnt dissaper when you select a server.

Screenshot: http://img44.imageshack.us/i/gmodbug.png/

Thanks in advance;

Ctrotter456