Problems starting Gmod

Ok, I start Gmod and the game freezes on the loading screen, it never advanced to the main menu, the loading screen just locks and the game hangs if i alt-tab.

Current system:
Windows 7 x64
i7 2700K
8gb DDR3 RAM
Radeon HD5870

What I’ve tried:
Removed all mods and content
Deleted garrysmod from steamapps
Verified game cache
deleted client.blob
Changed DXlevel
Restarted steam
Rebooted system
Updated video drivers
Updated DX11

I’m out of ideas, what the hell is freezing my game on startup? I’ve managed to get it to successfully start twice out of over a dozen times in the last 2 days. And in a few other instances i’ve managed to get it to start and begin to load a game, but freeze while loading resources. Please help

No one has any ideas?

The Radeon HD 5870 is know to have problems with gmod for some reason.

That’s a bit peculiar, I’ve had this video card for over a year and played 50-60ish hours of gmod on it before I rebuilt my OS on the new RAID array. Never had video problems before…