Look around for any CEC, HEC, ARC (see the pretty TLAs at http://en.wikipedia.org/wiki/HDMI ) and try turning them off.
Also, try other HDMI ports on the HDTV as some makes don't put CEC on some ports.
In short my bet is some HDMI control system is doing it's interference run.
Bob
I hooked the new 60" PN5300 plasma up to my Verizon Fios box and it wont change channels now??!!..Something is interfering, because as soon as I unplug the TV from the cable box, the channels work fine!!..Anybody else ever experience this??

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