levels - what a headache!

Movie_1 plays on the main timeline with a load movie action on the last key frame loading in the interface level_20. I presume the main movie is automatically loaded into level 0. On the interface there are 5 options with all buttons loading in their relevant swf's into level 10. The problem is with the home.swf. It is identical to the original movie_1 but loads into level_10. What happens is that prior to the home.swf loading, movie_1 becomes visible. This does not happen with any of the other swf's. What is going on.