Flash 8: Loading swf into swf

The loading works fine but some of the resulting behavior is curious.

level 0 - login.swf
level 1 - menu
level 2 - transactionA

Menu consists of buttons which launch load swf’s (transaction screens). If I launch transactionA (or indeed any of the transactions) and if whilst in that screen I click on a blank area that happens to “overlay” one of the menu buttons, that button responds! That’s undesirable - how do I prevent this?