One day I started FS2004, made a direct gps flightplan and started my flight. I like to fly on gps mode and just press the nav button. After I had taken off I put on the autopilot to let the plane fly its course, but as the plane starts to fly the gps course, it kept turning in other directions during the entire flight for no reason as if my course or heading kept changing. The flying tips kept telling me to press D to correct my heading indicator over and over again about every 5 seconds. I can't figure out how fix it can anyone help?

Well, is the NAV/GPS switch in the GPS position when using GPS for navigation?? Sounds like it is in NAV. Autopilot is therefore follwing the VOR1 when the AP NAV switch is activated. Paul

yeah I made sure i was flying in gps mode.But I figured out thats not the problem. The problem is my heading indicators are acting wierd. I have to keep pressing D to reset them. After I reset the heading indiccator the autopilot thinks it is off track and will turn back on track. For some reason it keeps repeating this over and over while im trying to fly.I dont know whats causing it?

You have Gyro Drift enabled. Uncheck the check box in the realism options within the sim and all will be well.Allcott