Since it's so erratic, I can't recommend much. Just try a reset on the player and make sure you're on the most recent firmware:
How to reset Smart Hub: http://www.samsung.com/us/support/SupportOwnersFAQPopup.do?faq_id=FAQ00045735&fm_seq=48449
How to update firmware: http://support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?idx=349421&modelname=BD-D5700&modelcode=BD-D5700%2FZA
I have a Samsung BD-D5700. Whenever I stream Netflix the sound will randomly drop and I have to hit the volume either up or down on the remote and it will come back. The BD is connected directly to the TV via HDMI and I'm using the TV's speakers for sound. The TV works fine when I'm watching digital cable, ect. and the cut outs are random - sometimes it will do it every 3 minutes, sometimes once a movie, sometimes not at all.
I've seen some different sound issues but I haven't seen this one. Is anyone else experiencing this? Any ideas how to fix it?