Ya that's a weird issue I've seen before I dont know exactly how to fix it but there's various way, I'm pretty sure if you clear the target_mc from the stage before loading the new swf into it it will fix your problem so one easy fix might be to add a blank frame at the start of your main swf give it a frame name of reset and then every time one of the buttons is clicked to load a new swf have it include a gotoAndPlay('reset') so that it clears the target_mc from the stage then recrates it before loading the new movie...hope that makes sense and there's alot of other ways to fix this as well...