Receiver outputs choppy sound in Dolby Digital

I have a Magnavox dvd vcr combo, with a coaxial audio cable going into my rca 5.1 dolby digital receiver. When I set the DVD player settings to bitstream, the audio is very choppy, but my receiver says Dolby Digital + Pro Logic 2. The DVD player says the bit rate is "48k/4". When i switch to PCM, the sound is fine, but obviously, dolby digital is not an option on my receiver. What is causing this choppy sound and how can i fix this?