I'm running Yamaha RX-V2600 receiver.  It is connected to Panasonic AE900 front projector using the HDMI out from the receiver.
Panasonic DVD player is connected to HDMI 1 input on receiver.  It worked perfectly out of the box.
I just connected a digital/HD box from my cable company using teh HDMI out on the cable box to the HDMI 2 input on the receiver.  A strange thing happens.  The audio is always there.  But, when that input is selected on the receiver, the video is appears only for 2 or 3 seconds.  Then, the image begins to flash, then the screen changes to all green and begins flashing green and does that continuously.  I connected the cable box using standard analog RCA type connectors to a different input, and it worked fine, but with a not very good image of course.
I called the cable company to see if they had any ideas.  Their only comment was that I needed to have a component connection together withe the HDMI connection, which did not make sense to me.
Please help with any suggestions!  Thanks!  Greg