BadenBr,
My guess is that you still have the autopilot engaged even though you believe you have disengaged it. I am assuming that you are disengaging the autopilot in the similar manner you have engaged it by clicking the button next to the letters "BALT". It takes a little more to disengage the autopilot once it has been engaged. The easiest method is to simply press the "Z" key on your keyboard. If you are dead set on using the buttons in the cockpit, I believe the "ON/OFF" button on the far right side of the Up Front Control Panel" will do the same thing. Once you have done either one, you should hear a disconnect tone/horn and you should have full control of your jet.
Hope this helps.