I have a similar issue, but through my older "fat" PS3. Our causes may be different, but our symptoms sound the same. For the short-term, try playing the same title, but go to the "Audio and Subtitles" menu in Netflix (shows up at the bottom of the options when looking at a show's detailed view - where the "Play", "More Episodes", etc. options are) and change the sound from Dolby Digital Plus (DD+) to Stereo.
My issue is that the old PS3 doesn't support DD+ due to an older HDMI standard. Ensure that your system / sound card can handle DD+.
Stereo isn't nearly as much fun as surround, but it'll be much better than what you're experiencing now.