2008 JBL - occasional Volume failures

My 2008 (78,000 mi) with original JBL stereo (with Nav) system has developed a strange problem, but one that is not unheard-of in other industries. Looking for some insight.

Occasionally the VOLUME will not function at all - neither the knob nor the wheel-controls when I power up the car. Every other function and button seems to work, though I have not fully tested everything.

This happens maybe once every three times I start the car, on average. The problem almost always disappears if I power the car down and restart it - that's what so strange about it. It's almost like a computer glitch rather than a physical connection problem, but I can't be certain. I live in central Florida, so while temperature may play a role in the contact electronics... it seems less likely as there aren't such huge fluctuations overnight - and, the problem seems to be arbitrary - it doesn't only happen after the car has been restarted cold - sometimes it happens after a very brief period of the car being turned off.

Any thoughts or insights? Is the head unit just going bad?