This has to do with the commander mode when you move with the arrow keys or the mouse. its really easy to go again, when your in the mode push the down arrow key and watch the movement. I have noticed that the movement is has a diagonal movement to it. You really notice this when you rotate your view to be parallel to the map. Now if you move left or right, it moves left or right with out a problem. It is only when you move forward or backwards, that it never goes true forwards or backwards. I would give a screen shot but, to show you what I mean I really need a demo.....