I used to have this issue on my old pc with a q6600 and 750 ti. I never did find out what was causing it.
I tried doing as you said and it seemed to have worked for a few seconds, then I tried to exit and open inventory again and the odd colors started up again.Okay so that might be caused by multicore concommand, which we have forced on lately - try running this in the console:
Let me know if that fixed it, it's a strange error.
I already have CSS.Hey Doodle, thanks for posting this. Hopefully, this can resolve some problems in the future.
It looks to me like a texture error. Can you answer a couple of questions for me?
Do you have CSS installed?
Do you have any other texture errors?
Have you tried deleting all of your addons and restarting the game? (When I say delete I mean just out of the folder, not unsubscribing.)
When did this start? When you first got on, or mid-game?