My IROC mod crashes to desktop:
Check the files and file sizes, in your "irocheat" folder...  There should be no files in the folder with a file size of 0 kb.  If there are, the simple fix is to copy that same file name from your RUN or DATA folder, into the irocheat folder.

  You may also have a problem with how you videocard handles the game.  You can try editting your Options.cfg file in the irocheat folder to change the following:

  If your races are very choppy, it might be your videocard can't handle the hi-res textures... try downloading and installing the alternate 512 or 256 resolution texture from the main IROC Heat page.