The phenomenon happens because of the way the particular driver you are using is defining the paper width and height. I noticed this while programming our plot routine. For example, when querying the width and height in code we may get 17" and 11". Then with another paper size, we may get 11" and then 17", but AutoCAD does not catch this difference on preview. We had to calculate that the width was greater than height and then plot landscape or else rotate the drawing. Selecting another driver may fix the problem. It was very annoying until we figured out the flaw.
Good luck