Hi: For some reason, the Cessna 172 gets completely crazy performing lesson 4 (stalls and dive). I am climbing at 75 knots (although it can happen in any other situation) and, SUDDENLY, the pitch increments VIOLENTLY, leading to a stall in one second, without even touching the controls at all. Just like a crazy horse. Am I doing something wrong? Is there anything wrong with the scenario or something else?