Display Problem

I recently got my logic board replaced and when I received my computer back two displays showed up in my system preference panel under arrangements (even though nothing is plugged in). The "external" display shows up as a VGA Display. The only reason that this is a problem is because I cannot get my LCD projector to project an image anymore. The projector is receiving a signal but it only displays a black screen. If anybody has any advice for me, I'd really appreciate it.

Thanks!