Some questions for you and hopefully it narrows down to the problem:
- are you running 5.1 or 5.1 plus 2 additional for "B" speakers?
- if 5.1, are the two front speakers connected to "Front Speakers A" terminals?
- is Speakers "A" indicated lid up and not A and B?
- are players (Fios and PS3) audio output set up correctly?
- are both players connected to receiver directly via HDMI cable?
- what indictors lights up on the display panel when playing a source?
- on the remote press "Receiver" and then "Display" (repeatedly), what audio format and listening mode does it show?
- is HDMI Control set to On?