Try to force a shader rebuild, by removing this folder, when the simulator is not running:
%LOCALAPPDATA%\Lockheed Martin\Prepar3d v4\Shaders
Then wait a minute or two (a black screen is normal) for the image to appear. Also, do you use any 3rd party shader modifications ? Those can also possibly cause those problems, especially if they are not guaranteed to work with the exact version of the sim you have.