I came across this problem a few times that 990 did not switch to the right decoding, after I had chosen the analog, stereo by-pass, on cd listening the night before. I hit DVD on the remote, 990 shows the right signal path to DVD with default digital decoding format (i.e. DTS), but no sound from any speaker at all. I had to either flip to other source (say vcr or CD)then flip back to DVD, then sounds came back.
It is not a real big problem, but would share with you all.
Kwok