Inverter system failure

My solar system is 4 years old.  It consists of 2 Kyocera 140 watt 12 volt panels; Morningstar ProStar 30 amp 12/24 charge controller: and a Morningstar SureSine 300 watt Sine Wave Inverter. The service panel is a Midnite Big Baby Box with Midnite VDC breakers for the panels to controller circuit; controller to battery circuit; and battery to inverter circuit.  The batteries to inverter circuit is also protected by a 110 amp DC fuse. The system sees only occasional and limited use and the two USREGC2 battery are very rarely discharged below 90% as measured by a Trimetric TM-2025. The inverter has a remote off/ on switch.  Other than a high voltage disconnect on a very cold and sunny day several years ago, the system has worked without a hitch. 

A couple of days ago the inverter shut down.  The demand on the inverter at the time of the shut down was low and no breakers tripped.  The AC Output LED and the Status LED on the inverter were both red, indicating (per the manual) an Inverter or System Fault.  I shut the entire system down and, per the inverter manual, disconnected all wiring to the inverter and removed the cover to check the fuses, all of which were intact. After putting everything back together and restarting the system the inverter worked as it always has.  A day later it failed again, again showing both red lights.

When I then began to shut the system down for a second time by first flipping the panels to controller circuit breaker, the inverter came back to life.  That didn't make sense to me and I suspected a loose connection of some kind.  I went ahead and shut things down and checked for loose connections.  I was able to get a feeble squeak out of two of the breaker terminal, but I would say everything was dead tight. A day and a half later the inverter shut down for the third time and the shutdown was again remedied by flipping and resetting the panels to charge controller circuit breaker.  When the inverter is on and working properly it is unaffected by opening the panels to controller circuit. Opening and closing the inverter to battery circuit would not restart the inverter after these failures.

Any ideas as to what's going on?  The system components are housed in a tightly closed cabinet in a cellar under my cabin. They get cold but rarely as cold as freezing, never get hot and are not subjected to high humidity.  The SureSine is hardened against harsh environments anyway and looks brand new, inside and out.  I would conclude that the inverter need repair (is that possible?) or replacement if not for its behavior in response to the panel to controller circuit.  Should I replace the panels/ controller circuit breaker?  It doesn't make sense to me. 

Thanks - Bill