How to tell if a level is already occupied

ok, i’m back again… and more stuck than ever. :{

i have a menu, and a content area. when a selection is made on the menu, an external clip is loaded overtop of the content area and does an opening animation. the problem is, when another selection is made from the menu, the animation starts the opening sequence over again.

what i’m looking for, is something that says ‘if level x is empty, load this clip and play it from frame y. if something is already loaded in level x, play it from frame z’.

anyone have any ideas on how i could approach this? thanks for your help!