Put flash in the Background?

I have a drop-down menu that uses javascript, but i also have a banner right under it, so when i go over the menu, the drop-down menu appears hidden behind the flash banner, and not accesible to anyone?

is there a solution to this?

Question 2: Is it possible to have two different flash banners, and have them change/swithch when the user hits refresh, so something radom that is?!?!

Thanks