Well, here's another attempt. In this case, I removed the top coat for the iris, the sclera, the lacrimal, and the pupil. I got the same result. I also get these same two Error notes in the Log File. Could this have something to do with it? 

[2012-09-06 06:20:14 Error: 2] Error hashing file '/Users/~/Library/Application Support/DAZ 3D/Studio4/temp/d2.tif'

[2012-09-06 06:20:14 Error: 3] Unable to open image file '/Users/~/Library/Application Support/DAZ 3D/Studio4/temp/d2.tif'

 

This scene renders just fine in DAZStdio4.5Pro, by the way. There's nothing wrong with the eyes in that app.