You might start with resetting your shaders, by removing this folder:
%LOCALAPPDATA%\Lockheed Martin\Prepar3d v5\Shaders
They will be recreated on the next startup, sometimes it fixes graphic issues. If that doesn't fix it, you might try resetting all your settings to default, by running the "Delete Generated Files" command in the P3D root.
This will reset all settings to default, so you'll likely see many questions about re-enabling your add-ons on the next start, at least the ones with their add-on.xml in the Documents folders, but you might have to reinstall\reconfigure those that don't or don't even use the add-on.xml method at all.