I get this as well with my Denon rcvr, it happens at the beginning of any Movie and then as well throughout the movie here and then I get audio dropout constantly for a split second or two. Yes! and when I start a movie or playlist it is the same, no volume control for a couple seconds into the movie.
I wish now I had taken notice when I had the Yamaha in place of the Denon. But it is related to the PC, if I switch to a Live control of a DVD player or STB from LMCE the problem is not there, it is only when streaming through LMCE from Network Storage it seems.
I am going to start to track it and note when it happens and with which device it happens.