Does this concern AC3 sound?
Check with a 'problematic file' loaded:
(rightclick >) Options > Filters > Advanced
Clicking on the small [+]-signs will reveal further info and/or open possibility to access settings.
Also have a look at what you selected under:
(rightclick >) Options > Preferences > Audio
"For AC3 decoding use" (in the south-east corner)
and also as "Output Device" under (as above) > Output