Check the settings for ALL devices and kill CEC, ARC, anything that could possibly cause this- if you have a Roku, turn off HDMI control and synch. I left CEC on with the bedroom Roku/TV without realizing it, might be a WBox thing (I decided to try one- it's OK)- can't change the aspect ratio and it sounds like crap.

Pull the power cord from the system and see if it goes back to semi-normal. I find that this is helping more often than I would like, lately. I have a customer who usually can't get the system to work when I'm not there but when I go, it works fine. Pissing me off and making me want to be a truck driver.