Temperature settings reset to zero mid-print, print head freezes
I have begun using a Prusa i3, Mk1. Several successful print runs, and then twice in a row, about 20 minutes into a print:
-- the print head freezes, even though new coordinates are showing up constantly on the LCD screen (as if the processor is still receiving and processing data)
-- the temperature settings shown are suddenly both at zero and the measured temperatures begin plunging accordingly.
I see no way to recover.
This seems a very strange combination of events. I appreciate any help!