Music within movies getting unsynchronized

When I place a movie with soundtrack (as one unit) in the timeline and then add a title slide or a slide before that movie, the music track from the video automatically extend to the previous slide and causing the music to be out of sync with the movie. My only solution at this time is to make sure I have all the slides (titles and others) inserted in the timeline then add the movie at the right place. This is not fun at all making montage with slides and movies almost an impossible task since we cannot move anything around without messing up the sound track. Please fix this, it's urgent.