The last two times {over the last 3 days}, I've played this "guest" player, I've mysteriously lost on time; who in turn, may've figured out how to cause his opponent's clock to 'run,' while it's his turn to move{!?}
 
This twice-in-a-row screw-up, made it necessary for 'me'..{excuse, the English syntax}, to activate the refresh/reload function {the second time around}, where it became apparent that either this particular player knows how to 'game-the-system'... or alternatively, something's amiss with my own, or 'Caissa's' software{!?} ..