When I connect my Macbook Pro to my projector, it works fine for Keynote or PowerPt, but my desktop goes wonky, with the thumbnails becoming oversized and overlapping each other. During keynote presentations, I need to revert to my desktop to play audio or video samples, but because of the aforementioned problem, I can't without unplugging the projector, which is kind of a pain and appears bush league. Figuring it must be an adjustment thing but don't know how to fix it. Can anyone help? Thanks.