My 2013 R56 S has the Harmon Kardon radio upgrade, no navigation. A couple nights ago, while I was listening to MP3s on a flash drive, the system turned itself off, going totally dark (except, I think, for the clock), then came back on several seconds later. All settings seemed intact afterward, although it started playing a different MP3 in the same folder. I replayed the entire folder, thinking somehow the cause might be a bad MP3 file, but it worked fine.

This is the first time that has happened in the 6-1/2 years I've owned the car. Has anyone else experienced this and discovered what caused it?

 

Still running original battery? If so get it tested as that is a first place to look for electrical Gremlins.

 

No, the battery is just 6 months old, and was replaced by the dealership.
Also, I should have mentioned that I was driving the car at the time, so the radio was not running on the battery.