FSX problem Plane engines

Microsoft Flight Simulator X
Problem: After playing the game for a while I have to manually start the planes before takeoff. When I first installed FSX the planes were automatically started on the runway which is the way it should be. I put in the DVD and went thru the Repair process but that did Not take care of the problem. I have to uninstall and reinstall the whole game to fix the problem and after a while the same problem comes up again. There has to be a file or setting that the repair process will not fix I wish someone will come up with an easy fix I’m kind of tired of uninstalling and reinstalling FSX and that’s not a very fast process.
I’m using Windows 7 64 bit. And when I used Windows Vista 32 bit I had the same problem.
Thank You
Nick
nicksat@sbcglobal.net