On rollover button issue

I have a series of dropdown menus (horizontally placed across the movie). Upon selection of one of the sub buttons, a corresponding scrollpane and also an empty movieClip will appear below, taking up most of the movie stage. The scrollpane has buttons that call different movieclips into the emptymovieclip. Also, I’m going to make it so upon selection of a sub button the menus go back to their closed state above.

How, though, after the user is done viewing the scrollpane and empty movieclip contents that may be called… how, if they should roll over another menu, can I have it simultaneously unload whatever scrollpane and contents of the emptymovie clip are visible? These will be different depending upon what the previously selected button was. So, a user may roll over “menu 1” with many possibilities of what is showing in the scrollpane and the emptymovie clip …due to the most recent selections.

I thought about a back button, but what if they simply go to the menus and don’t use the back button… then the menu will drop down over the current scroll pane and movieclip and it won’t look right.

I also thought about removing the menus once the scroll pane and movieclip have opened and then the user would be forced to use the back button, but… that doesn’t seem as user friendly.

as always, I’d appreciate any suggestions… thanks.