The following error occured to me lately when using the Cheyenne:
The GPS would not show any distances or directions to waypoints in the flightplan. Also the navlog page on the WX would show 0.0nm to every waypoint. In addition the WX would not show anything, not even the test screen. So, at first i thought there may be an corrupted installation and reinstalled the plane.
But in conclusion FSUIPC (v3.90) was found to be the reason. Since i just recently registered, it must have been since then, but i only just this weekend got the cheyenne out of the hangar after a long time.
Now to fix the problem i removed the registration from FSUIPC temporarily and everything works again. Of course, afterwards i dont have any weather options or joystick buttons or joystick axes. So i would very much appreciate a different solution.