I am running DX11.
If you use FSX, you run either DX9 or DX10, while if you use P3D 2.0, you run DX11, but then of course you wouldn't need the DX10 fixer in that case.
I guessed it might be something related to the DX10 fixer, because there was a very recent thread (which I've linked) that looked very similar to your problem, and you haven't said if you use FSX or P3D.