DVR is the audio source? That's your problem then. Nothing down line would receive a signal if it didn't come from there.
I'd do a Google on your particular model DVR to see if you can find similar problems and fixes.
If ML hasn't helped you out yet, start with a sensible approach to troubleshoot the problem.
Easiest first step would be to swap the rear panel between speakers to see if the problem remains on the same channel.
You said the speaker played fine and starred causing problems after a few...