Probably on the turn? I have the same problems sometimes, but it's usually when I'm in the BB and have hit my TP low kicker.

I think I shut down because there are no drawing hands on the board, so he's either hit a set or two pair and is milking you, or has the better King as alluded to in the results.. he really can't have any less because not even bad players will put up that much of their stack on like 2nd pair.