Same problem here.
Nothing I can do helps, I've had (I guess) some success with tweaking config.cfg and setting the "mip" options to 0, from what I understand some of the textures still look like utter crap despite this. If you attempt it, after your changes go into properties and set the file to read only, or the game will immediately revert them. I don't know if perhaps a lot of people aren't observant and this is going on more than we think, or if it's a very unlikely problem.
But it will stick on low, just nothing beyond normal. I"m using the 4gb patch although that doesn't seem to be consistent with the problem, have a friend who is also using the patch and runs settings on max.
I5 760k 4ghz
4gb Gskill 1600mhz
7970 3gb OC'd to 1125mhz
Win 7 Ultimate x64
Thinking of uninstalling and reinstalling to see if this fixes anything.