Issue with Vudu movies

I have a number of movies on line and watch them through the Vudu service which I access through my Oppo-103. When I first connect the video comes through crystal clear but there is no sound and the 976 flashes back and forth from DISC to Dolby Digital, back and forth. It does this for about 20 seconds and then it connects. If I want to hear the audio I miss d I have to back it up. Once it connects its good but this seems like a long time to make a connection. This has happened multiple times. Any thoughts?