Deactivating buttons when another movie clip is ontop

Hi, I am creating a flash website and want my buttons to stop operating whilst the portfolio is open and is ontop of the other main buttons. I am just calling a function to add the portfolio as a movie clip ontop of the scene, at the moment you can click through it, using the buttons behind. I’m pretty sure I could sort this out using attachMovie/removeMovie for each button but this seems a very lengthy and time consuming method.

Any Ideas?

Thanks