Definitely at the receiver. You want to try and track down (if or) where the wiring problem is. This type of thing usually a wiring problem, but it can always be something else. Best to test the most likely cause first.
So, if you find that connecting a specific speaker leads to the...
OK.
The next thing to do is disconnect all the speakers and see if it still shuts off when you play a movie and turn the volume to 47. Then reconnect each speaker, one at a time, and see if it starts again. If it starts after connecting a specific speaker, that has to be where the problem is...
This could be difficult to troubleshoot. There's probably a flaw in the speaker wiring somewhere that's causing the receiver to go into protection.
I'm trying to come up with a likely thing that's wrong, but nothing is coming to me, other than just just check every connection to all the...