I was disposed to play Halo 3 with a friend in order to make a video, but the game disconected us not even on the half of the first mission, we could´nt finish the mission because when I clicked on resume, it started all the way back from the beginning and erased everything we did. The only good thing is that it gaved the achievments, but believe me: We could´nt play.
I don´t know if some of you had the same issue nearly on, let me know plz.