Just try it. It's like shoving a box full of goodies until it finally explodes, and when it explodes, time freezes. So you throw out some of the goodies, and it will be a safe box again. Hopefully. The box is your video card, and the goodies are stuff like high-res textures. If disabling the high-res textures didn't work, you're going to have to throw out more, or be absolutely certain your video card is good to go.
I remember a thread where there was a pretty long list of stuff to disable, I might be able to find it.
edit:
r_caustics 0
gl_stainmaps 0
gl_dynamic 0
r_oldmodels 1
Then vid_restart.