I have been flying my 737-400 for years using the IAS button in the Autopilot mode without any problems. I'd just set the IAS during auto pilot mode and never worry about my speed. Now all of the the sudden the IAS button won't light up or work unless I activate the Auto Throttle switch. Then, when I attempt to set the speed at anything above "000" the engines spool up (while sitting on the ground) and won't stop unless I disengage the Auto Throttle switch. Before, I rarely used the Auto Throttle switch, and would often activate the auto pilot after flaps and landing gear up, and then let AP take me to cruising altitude and speed. I would always preset my IAS at a designated speed and then turn on the IAS button prior to take off, along with the ALT and HDG buttons. Of course none of these would begin to work until I activated the auto pilot. Any ideas of what could be wrong with my IAS functions, and any suggestions on how to fix it. I have uninstalled and reinstalled the game twice, with no help. My 777 and Learjet are doing the same thing. Please help??