Sounds like something in the HDMI chain is generating bit errors. It may not be signal strength but instead a bad board.
Best way I know to track it down is to use a source close to the projector with an HDMI cable and see if that generates the error. If not, then back-up the same source and use the baluns. If no error then add the receiver.
I'm not sure you really ruled anything out with your test. Until you get to only two components (source and projector) to start with, it's hard to say what could be wrong.