Might just be that the game is too unstable itself. If you download a clean copy of the game and drag&drop the GFX and SFX folders from the modded ver, it may work. If not, run the game's .exe directly in the files. I may have marked it as hidden in the file explorer so people would click on the shortcut, so maybe if you check to make sure that your file explorer shows hidden files, then just run the game directly.