I also might note, but I'm not sure if this has to do with my problem or not, that the scene was set, in Reality, to be saved to "C:" something as one of those mesh light files. I'm on a Mac, and so Reality pointed out to me that "C:" etc. does not exist. I changed the location back to /Users/mydirectory/ etc.

Well, maybe that's another issue. It was easily taken care of, but could it possible account for the postage stamp sized render?