Startup crash. Help please

[Sanctus]

So I downloaded a driver for my old gpu finally, and decided to start up Gmod. But as soon as I see the citizen npc's back standing in gm_construct, the screen goes black and returns to my Steam Library. Can anyone tell me what's wrong?

[Rainbow Dash]

If I had to guess, I'd say it might just be something to do with the source engine/tf2 update that valve recently launched (http://forums.steampowered.com/forums/forumdisplay.php?f=80), which people have been reporting crashing in other games besides tf2.

Otherwise, try running in -dx8 mode or something.

[Sanctus]

Oh so it's another one of those "Valve screwed with the network" things again.