I have tried all that you suggest and some interesting things happened, I can now see oil and poison clouds, all other ground effects still don't show up. Additionally, outlines no longer appear around objects, and the main menu has a TON of missing textures. These changes are in effect even when I switch my video options back to the way they were before. I'm going to try a delete and re install tonight and see if anything changes. If you have any insights before then let me know, otherwise i'll report back after the re install.