Suddenly, things in 5.1 have this awful audio noise coming out of our rear speakers. Everything else is fine. The connections are fine. What’s going on?
NEED ANSWER FAST this sucks balls. (Seriously. I did the speaker test thing in the setup menu and sound came out of everything.) We have an LG all in one Blu Ray setup. One disc that had some stereo tracks in other languages was fine in Spanish and French.
We unplugged it and replugged it. It did change it - there was a burst of static at the beginning of the Columbia Pictures logo and then it died down, but when we hit play on the movie (two different movies) it came back.
Switch speakers and see if it still happens to the same speakers. If it does, it’s the speakers. If the effect moves to the new speakers, it’s the receiver.
Are your rear speakers wireless? If so something may be inducing a ground loop hum in them. Move a rear speaker around while it’s making the noise and see if that effects it.
Since you indicated that the speaker tests worked OK and alternate soundtracks were also OK, it would seem that the problem has to do with the main outputs from your Blu Ray player to the rear speakers. For normal playback what do you have your rear speaker channel on your Blu Ray set at?
They’re not wireless and it seems to be a problem with the receiver/Blu Ray player. 
I can post the settings tonight, but my fiance spent the morning on the phone with tech support for the player and got exactly nowhere.
Is it possible to buy just the player/receiver part of a home theater in a box? Seems silly to replace speakers that have nothing wrong with them.
The usual answer is to perform a hardware reset of the entire mess. If you have been on the phone to the tech support I would have hoped they would have suggested this. If they did, and the system is still behaving badly it is broken. This is not just a matter of removing power to the system off, waiting, and powering back again (although this is always a good first start,) but causing the processor in the system to reset itself, and to return to factory defaults. How you do this will vary, but is typically done by holding down a particular set of keys/switches whilst the system is powered up.
Yes. But it means buying a player and a receiver as separates.
The way the good Lord intended. 
Like somebody’s dad or something? 
Yes, they had him do a hard reset when he was on the phone with them.
Not clear on this but you have a single component that includes both the Blu Ray player and receiver circuitry? If you have separate components (Blu Ray player and receiver) you might consider checking the cables used to go from the Blu Ray player to the receiver inputs. They can short out or be defective!
No, it’s an all in one home theater in a box. No separate Blu Ray player.
Just a quick nit - there are plenty of HTIB systems that separate out the receiver from the bluray/DVD player.
Have you been able to switch speakers around to see if it’s something wrong with that particular speaker yet?
Yeah, it’s not the speakers. 'Im Indoors is going to try to call tech support again today and get a different person as a last resort.