I have a scene with 3 lights. 2 are spots with shadows off and one is an area light with shadows on. The Area light is an overhead light giving subtle shadows to rows of computer monitors. I'm using depth map shadows for this light. All of these monitors are on a circular platform which is turning slowly (like a turntable).
The problem is that the shadows are shifting slightly during the turning movement, almost like the area light's position is keyframed slightly every frame. The camera is locked down and not moving, and the shadows look close to perfect on a single frame still. I'm rendering with Mental Ray.