CoH: Modern Combat

I've had COH for a while, just realized there are mods for it. Got my friend into it as well. He bought Vanilla COH which cannot see my game despite having very literally the exact same files, installed the same way. Inviting him to my game results in an error message claiming we are running different versions of the mod (we aren't). Any fix for this? Buying the DLC is a tad expensive. Also, I crash within a couple minutes of playing a skirmish, no particular error, just dead. Playing in mutliplayer against AI works fine though. Any fix for that? I'd love to play the game with the mod, everything else seems so stale lately.

Are you sure your installation went well? It sounds like some files may have been corrupted. Did you also update to the latest version of the mod?