When I use some Mac Pro computers to project a Keynote going form the display port to the VGA adapter to the projector, the mirrored image is green and washed out. Using the HDMI output works fine. I've confirmed the adapter is not the problem
Sounds like a poor connection or bad VGA cable.
I sometimes get that on the VGA monitor on my Mac Pro and wiggling the connections resolves the problem
If all the VGA signals are not properly connected, you can get a colored wash over the entire screen. This is usually red (or pinkish) because the Red VGA signal is near the end of the connector, and tugging on the connector can dislodge the connection on the end.
If some other signals are out-of-bounds or too fast for the projector to deal with, it may assume you intended to supply composite video, and ignore red and blue and show only the green channel as the picture. Try setting the resolution to something really plain, like 640 by 480 or 800 by 600 and see if there is a change.
Mirroring produces a 'lowest common denominator" signal that is a compromise between what the projector MAY be able to do, and what the built-in display can do. It could easily be too fast for the projector. You should experiment with displays NOT mirrored to get more information. Then see if you can run with displays NOT mirrored.
ALWAYS do a rehearsal of important presentations in the room with the real equipment and conditions you will face "on the big day". Do your entire presentation just the way you expect to do it "for real", and time it.
Mac Display Port to VGA To Projector is green
