You have the "ray epsilon" in this scene (in the quality settings) set to 2. Is there some reason why you did that? Normally that should be a small value like 0.001 unless you have a huge scene scale. I think artifacts are related to that.
Hey thanks, that fixed the problem. No more dark areas underneath the rings.
I had it set at 2 because when i was working with interiors, I was getting realistic
renders with that setting. Ive been using that ever-since.