This site is being deprecated.
Please see the official X‑Plane Support page for help.
You can check your system requirements for X-Plane 11 here. Try to reinstall your graphics card drivers and/or change settings by turning off threading optimisation (for nVidia graphics card open the nVidia Control panel, select Manage 3D settings on the left, select the Program Settings tab on the right, select the X-Plane profile and turn Threaded optimization OFF).
This site is no longer being actively maintained.