Friend & I Cannot Play Halo 3 Specifically

A friend and I are able to play Halo 3 on our own just find, with no issues whatsoever, same with playing with other parties, etc., playing customs and multiplayer work equally fine. But when we party up together, the match will begin to load, the loading bar will slow down, stopped at Validating, then cut to black and kick us out into the main menu. This is a consistent and reoccurring bug for us specifically, nothing is wrong with either of our Halo 3 files, and I was wondering if anyone else has been encountering this issue and if there are any solutions?