I downloaded windows 8.1 and everytime I start FSX. This picture shows what happens.

 

I try turning the 3D off and this happens: The next Picture.

 

And when I do that fsx then does this. 3rd Picture

Go into Nvidea control panel and disable steroscopic 3-D. for some reason, it set it to on (did it to me too).

 

Edit: sorry, didn't read that you'd already done that.  Have you updated Nvidea drivers to the latest?