May be way off here but.....
the cover story "A Practical HDMI Cable Solution & Installation" mentions something simalar though did not mention if he had audio or not just that no picture.
From that story:
"The Problem
Oh how wonderful it would be if that was actually true. I ran through all the video inputs using Yamaha’s scaler and had no problems with the TiVo, the VCR and the DVD Player. Then I went for the gusto and switched over to my long awaited HDTV. That’s when the fun began. When switching video inputs I noticed that the HDTV tuner was unable to lock onto a resolution. I nearly cried out loud. Before doing so, I called DirecTV to see if they could offer some assistance. After going through their advanced support center, we went through one simple test. The tech person asked me to connect the tuner directly from the HDMI cable to the TV therefore bypassing the Yamaha. And there it was; a picture. I was able to lock into any resolution I wanted with no problem. I then went back through the Yamaha and the same problem manifested again. DirecTV passed the buck at this time indicating that their tuner was doing its job. They were right... to a point.
With no where else to go I once again visited Audioholics to see if anyone else had this very same issue. It was then that I found an entire forum devoted to this same problem. It seemed as if almost everyone with an HDTV tuner (cable or satellite) has experienced the very same issue. The staff of Audioholics saw the forum grow with many speculations so they contacted Yamaha directly for information on what was going on. From this I learned that my brand new DirecTV H20 HDTV tuner was not compatible with my equally as new Yamaha RX-V2600. You see, this and many other HD tuners are not equipped to work with HDMI repeaters - which, in a simplified sense, is how the Yamaha behaves with respect to the satellite receiver."
Goes on to mention something about firmware upgrade. Goodluck hope that helped, if not I apologize.