I woke up this morning to by BJ fan turning off an on.  Last night I got the 3.12.0hf3 update and since then the miner mines for about an hour and then restarts.  It's not a full RPI reboot, but cgminer crashes/quits then restarts.  The cgminer restarts seem to be about every 75 minutes or so. I'm running stock clocks.

Since the automatic update I'm only getting about 350-370GH/s.