I would suggest to use ActionScript to do this. In the normal Flash interface mouse events can only be added to buttons not movies or canvas objects. This is a complicated subject and there are many ways to do this. You need something like this (has to be modified, it is generic code):

button1.addEventListener(MouseEvent.MOUSE_OVER, openMenu);
button2.addEventListener(MouseEvent.MOUSE_OVER, openMenu);
...

public function openMenu(event:MouseEvent)
{
     switch(event.currentTarget.id)
     {
          case "Company":
               movie1.visible = true;
               movie1.play();
               break;
          case "Whatever"
               movie2.visible = true;
               movie2.play();
               break;
          ...
}

movie1.addEventListener(MouseEvent.MOUSE_OUT, closeMenu);
movie2.addEventListener(MouseEvent.MOUSE_OUT, closeMenu);
...

public function closeMenu(event:MouseEvent)
{
     event.currentTarget.visible = false;
}

I suggest you read up on Action Script. I am not very familiar with doing menus or other complex things without it. Not sure if it is even possible.

Good Luck,
ST

I found the error. Removed the on (over) behaviour from the mov_company stage object that caused the error. now it works.

see attached fixed file (rename it to nav.fla after extraction)

This was the behaviour that caused it directly on the mov_company object on stage:

on(rollOver)
{
      mov_company      .play();
}