I am only a 2D ACAD user, but curiousity got the better of me and so I was playing around in the 3D realm and now I have a gray background that I can't find a way to turn off. Wish I could tell you what I did to cause this, other than telling you that I was fiddling around with the ViewCube and 3D Orbit. Feeling pretty dumb at the moment. Help?