I think it's just vsync off. You are rendering at an higher rate than your monitor can display, so what you get on the screen is actually a frame on the very top and the old frame (or more) at the bottom. This is also why you see this when things are rotating, because it is maximizing the differences between frames.
This is perfectly normal, to "fix" it pass 1 instead of 0 as first parameter in your "Present" call at the end of the frame. This will sync your rendering with the monitor refresh rate and the lines will disappear.