He jigs. He will ram me into tree trunks. He'll halt and wont move forward, and will start backing up nonstop. He'll side step down a narrow path - just silly things.
When he has a mentel meltdown, I usually have to get off and walk with him, then after a bit he'll come back to his normal self and be ready to head off politely to finish the ride.
Also, when he has those mental meltdown's, I have to sit as quiet as I can on his back and just leave him alone. The more I fight, the worse he gets - so one has to learn to be very patient and calm.