I recall a rather lengthy debate earlier about Pro Logic IIx in relation to another product, in which it was said that PLII and IIx were only required to work with Dolby 2.0 and 5.1 sources. Having said that, though, I'm also not sure how many times a 990's been fed a Dolby Digital 3.0 signal - it's very possible that the 990 could apply PLIIx without losing the dialog even though it isn't technically required that a PLII/IIx processor be able to do so, and that what you're encountering is a previously-unknown bug. I'd try confirming it in my system, but I don't have any material in my library with a Dolby Digital 3.0 audio track - where did you come across one?