Sometimes, not always, FSX starts doing things by itself. Yesterday I was flying a Cirrus at 13,000' and the engine started surging and quitting all by itself. I usually see this when flying something like a B737. I stopped the flight and repositioned at the end of a runway. The engine kept on surging and started to take off by itself.The first sign of the problem is getting a message "differential braking." Then other things start happening.I checked and the reliability is set to 100% (no failures preselected).The tech details are:XP ProFSXAcceleration PackThis problem was happening both before and after I had to reinstall XP Pro and then do a full new install of FSX.Any idea what is going on and how to fix it?

What are you using for throttle control? If it's part of a yoke or joystick controller, try flying without it using the keyboard.

If you are using FSUIPC, try opening to the calibration tab and then closing it.It looks like your USB ports are not stable and varying the throttle inputs.From here it will be a trial and error trouble shooting event.Does it happen for all planes?

I am using the Cirrus II Precision Flight Controls & rudder pedals (B-ATD) along with the PFC software interface. I have seen the problem on the B737, the Barron and the Eaglesoft SR22 add-on. I don't recall seeing the problem with the C172.