I have my Video 2 source setup to playback video from my cable box. Audio is input via Coax 3 from the same source. In the Input Configuration, I set the default surround sound mode to "Dolby Dig EX" -

randomly my receiver seems to reset to one of the Dolby PLII modes. I don't run a 6th channel anymore and there isn't one configured in the setup. Any ideas?
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Model 1070
Toshiba HD-A35 & Pioneer BDP-51
Tivo Series 3
Elite 50" / Aquos 32"
Squeezebox Radio

Stereo Setup:
NAD C326BEE (50Wx2)
Elite DV-47Ai Universal SACD/DVD-A
Citypulse DA7.2x II + TXCO DAC
B&W 685s
JL Fathom F112
Denon AH-D2000 Headphones