What caused the unmovable diagonally striped background?

Ever since the update, my project has been real buggy, it would frequently crash after I press the play button. I figured I must have an error in my level so i started a new level in the same project. Everything works fine but now this unmovable fullscreened background shows up and I can’t get rid of it until i close the project. The only way I can move it around is if i switch between my three monitors. Any ideas what is causing this?

Gee Whiz that was a fast response, and I guess I should have looked harder, Thanks a lot resetting the UI Layout fixed it!