It seems to be a weak point of the 272. I encountered the same problem some weeks ago in my 272 from May 2016, which jumps 'out of the blue' to MUTE+PAUSE. In other words, the sound is muted AND the music is paused. Did a couple of tests:
When I copy some songs onto a USB stick and play the songs directly from the USB stick in the front panel, the same happens --> the problem is not in the NAS or in its connection to the 272
When I remove the batteries from the remote control, the same problem happens --> the reason is not a faulty signal from the Remote Control
The problem seems to occur after several hours of playing. When I switch off the 272 (using the switch at the back) and turn on after some minutes, the same problem happens.
Phil Harris from Naim suggested that the 272 unit has a faulty touch logo and the logo is incorrectly registering a mute touch. And indeed, after I disabled the mute button under Settings, the problem was gone.
My kind dealer offered me a free repair under warranty, but I didn't bother.