How i stop a main-movieclip while i run another animation?

I use Flash 5:

My mainmovie clip is: mainmovie

The button on the navigation to load the swf-file (second animation) has the following code:

on (release) {
loadMovie("brillen.swf", "_root.Target_screen");
}

Everything works perfectly but how can i stop the "mainmovie" while i run for example "brillen.swf" and so on?

And how can i start the "mainmovie" again after the animation of "brillen.swf" is finished?