Simple Drop Down

Newbie here. Having problems with drop down menu. Sorted out like this:

menu 1 : menu 2 : menu 3 : menu 4
submenu submenu submenu
submenu submenu submenu

each menu is a MC. when roillover event occurs, goes to next frame (small tween effect) then stops. Rollout invisible button at this point that borders the entire menu.

The problem I’m having is that when I rollout to go to menu 2, sometimes the submenu on menu 1 sticks.