What's happening!?

[el Chi]

I tried to play HL2: DM today and... Well, look at the screen shots to see the full graphical hideousness of what happened.

It wasn't doing this yesterday, and all I've done since then was install Garry's Mod 8. However I played that just after installing it, and it didn't do that.
Any ideas?

 

[$kelet0r]

that used to happen to me in games where the card didnt have enough onboard ram
i dunno - might be just a one day glitch

 

[G-Dub]

You tried re-installing your GFX card drivers?

 

[Jangle]

that happens to me if i minimise the game window and then put it back up again. Just try starting up the game again

 

[BlackStallion]

yeah in source when i minimize source thing have purple things.