I've been looking through the boards and their history and can't seem to find anyone with this problem. All I'm doing is turning on Mental Ray, and my renders of non-transparent objects are coming out transparent. It doesn't seem to have anything to do with the lights, textures, materials or Render Global settings--I've tried several different of all of these. I've used mental ray before without this problem, on a PC, now I am using a (very nice) Mac, if that has anything to do with it (don't know why it would). Anyone know what to do about this?