Used my geek squad account at Best Buy to get help to resolve this on my LG blueray player where I had the same issue. (I have the same issue wit LG and Sony players. The trailers and ads have great sound but the minute the movie starts there is no sound. Has absolutely nothing to do with equipment because, as stated, ads and trailers have great sound and I never have an issue with DVD format.) What fixed the problem which I understand is different from brand to brand was this. With the disk out we first tried to do a software update. Then, we tested if that worked to update the audio settings...it didn't. Then we went to the home button and in that selected settings and then scrolled to audio. In audio's "digital output" we changed from AUTO to PCM. And, that fixed it!