Audio on hd dvr

[johnny58259]

I got a hr 21 pro and this morning something strange happened the audio was real muffled shakey sounding. I changed channels still same thing. I had left the receiver and tv on overnight. To fix the problem all I had to do was turn the receiver off and back on. Any ideas why this would happen or just a simple glitch.

 

[raoul5788]

Gremlins.