Fullscreen flash background

Hey guys,
I have this flash piece ive made for a cd that I have keyed to autorun.
I want the background to fill the screen when the user puts the cd in the tray but not have it make the flash interface go fullscreen I hope that makes sense. In the screen below it shows the flash interface opening fullscreen and on the right just the background filling the page with the interface center. Im sure its easy but could anyone give me some help?
Thanks,
Chris