What's causing my Dolby modes to change?

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?

I'll take a stab at this, just off the top of my head.

Dolby Digital EX can only be used with a Dolby Digital 5.1 source. The only 5.1 sources you'll see on digital cable are HD channels (and even then it's not guaranteed). The rest of the time, you will see a mix of Dolby 2.0 and PCM stereo. In those cases, it is using Dolby Pro Logic II (or PLIIx, which is the exact same thing in a 5.1 speaker setup) to produce a 5.1 source.

By the way, if you no longer have a rear surround speaker configured, Dolby EX won't be showing up anymore anyway. Some Dolby EX DVD's may try to engage it because of the way they're flagged, but that'd be the only case, and even then it won't actually do anything (in fact the 1070 may be able to disregard the flag when configured for 5.1 output).

never said thank you Gonk - so thank you.

You're most welcome, Red.

I've just applied the newest firmware code and I'm having switching issues as well... worse than before.

Whenever switching channels on the cable box or pausing/ffwd/rewinding a dvd the digital signal is "lost" at the receiver and it tries to kick back to a Dolby PLII-M. Whenever the receiver notices the signal again it will pick it back up and everything is ok. Problem is, there is a several second gap that it goes through for this to happen. Annoying to say the least. This was not happening nearly as bad before I flashed the thing. Any ideas?

Also, I don't have a 7.1 setup, but for some reason the receiver always shows the PLIIx options. I have the Surr Back Size set to None and the Surr Back Out set to None as well. Is there something I am missing?

If I am not mistaken, I believe that you must go into the menu and turn the auto poll(ing) off. I noticed this same delay with the 970. Gonk, led me to the Auto poll menu selection - problem solved, for me at least.

I concur with nomoneybutgoodsound - disable auto polling for each input (unless the input happens to need to be able to use analog inputs when the digital output is inactive, such as some early digital cable boxes when viewing analog cable channels) and see if that helps.

Yes. Perfect! Thank you!