Interesting. I've checked out some gameplays too and I can actually confirm that some sections do miss fog and rain effects on PC, so your mod might be one of those essential ones. I'll add it to the game's main article.
Very strange indeed. I honestly am not sure how to help you. You might try removing those d3d dlls and play in native DX8 mode. Also, check if antivirus haven't blocked any files in the game's folder.