Fullscreen mode stops buttons working. Help!

I am using Actionscript 2 in Flash Player 9.

I have created a movie which preloads then plays a very short animation.
When the user clicks an ‘enter’ button it goes full screen.

However, from within Flash the buttons work ok, but when it goes live on the server, when Fullscreen is called, all the buttons stop working. (they are movieclips with actions against them, not actual button clips).

Has anyone got any advice?