How do i get to play user created content on xbox 360 halo 3?
This is what I think. It may be that person who “cant play because of user created content” had set on their parental controls to disallow user created content, eg forge maps made by other people etc, and so it wont let you access anything user created with them. Make sure that person has taken that control off, don’t play with him, or only use default maps.