silence is good, but i think (please test and report back!) you can start your DVD with two seconds of black video with AC-3 sound, as long as all sound on the disc is AC-3
(the decoder has to switch.)
Always a good idea, since the specs state first play has to be a video stream.
I do this always, but just to be safe. Over here (Pal land) i never had the problem...
Bouke