Did you delete the cache after reinstalling the game ?
Usually the good way to do it is :
- Make Steam check your files
- Let it download the files that need to
- Delete the cache (located in My Documents\1cSoftclub\)
- Run a free flight, shoot somme guns, fly some dust (cache file will recreate itself with the new shaders)
- Exit the game
- Restart it, and Voilà !
I think Steam is not touching the user files located in my documents, so you need to clean the mess for the previous version yourself.
Do you have graphic bugs in some other game?
Cheers