Sometimes when I'm flying, I'll have autopilot, flight directory, altitude hold, NAV hold and speed hold on. I'll be flying and my speed hold will go to 195 knots or switch off. Then I get a stall warning at 300 knots, and an over speed warning at 301 knots! Then the plane will start doing things not possible, like moving up at 500 knots with the nose down, and moving across the country without even banking. It just happens for no reason!
Please help, I'm new to flight simulators.