No boot screen while Cinema Display is connected

Hello ifixit community! I am having a very annoying issue with my Power Mac G4 Cube and Apple Cinema Display. Whenever the cube is connected to a VGA monitor, I get a proper boot screen, but whenever the Cinema Display is connected there is no boot screen but the screen displays a picture once OS X has booted up. I have tried everything from reinstalling Mac OS X 10.4 to replacing the CMOS battery to resetting the PRAM. The weird thing is, I remember the Cube showing a boot screen on the Cinema Display just fine before attempting to install Mac OS 9. Any help is appreciated!