This is a mystery. Do you have another monitor, even a small LCD monitor, that you could connect to the X4300H and test with? If the LCD monitor is jittery, it might very well be the AVR. HDMI is a cranky interconnect in the interface circuitry. (I think the designers were worried more about content protection than display quality and convenience for users.) But then again, the problem only occurs on Sherlock. If the LCD monitor is fine, the projector becomes the suspect.