Generally the skewed "gray background, right of center, stretched out "flat" to the right at about a 20-degree angle." issue has always been the result of using autohide but if you know 100% you have taskbar locked and you have "automatically hide taskbar in desktop mode " OFF then you might want to check your graphics card which you can do yourself
https://www.youtube.com/watch?v=_kCcrEg3E_k
Also try running task manager while you run the game to see if you start pulling high numbers and make sure the game has enough memory