I changed my settings to PCM Stereo a month ago and have had no problems since. Heat issue in the Dolby circuitry - maybe; the heat may have prematurely aged some of the components. HW issue - maybe; many designers reuse circuitry across devices - I know I did. SW issue - maybe; with the heat and circuitry components degrading, a software setting might be at the edge of functionality so that when the circuit changes, the software doesn't run right. Issue with a software upgrade - maybe; many companies do regression testing only on the part of the software that they changed, not across the entire platform (saves time and money if they get it right - get complaints like these if they don't). Also both the hardware and software can get to a logical state that can be reset with a power cycle. The idea of leaving the unit unplugged for 10 minutes is an old one that was valid in it's day - large capacitors needed to discharge their stored energy. With integrated circuits the capacitors are much smaller as are the voltages.
Again, I changed my audio settings from auto or Dolby to PCM Stereo and the issue has not repeated.