I've also updated the firmware and I've noticed a perhaps related behavior. When watching Comcast OnDemand HD music videos, even though I have the 990 set at Dolby Digital, when a new video starts, it will switch to PL II Movie -, which is not a good match for music. I then manually switch back to Dolby Digital.

I've looked in the Video1 setup and it had surround mode set to SV Wide.

Is there something in the HD video content that causes the 990 to detect something and switch modes?