I don't think this has anything to do with geometry, reflections or raytracing.

I was working on a scene, with one David one Paperoll from Render Studio for Poser... and just a bunch of lights.  No reflections, nothing odd... and the render was fine until some point, it just decided that it was NOT going to finish precalcing the indirect light.  No matter what I did, once it was done... it was done.  I backed up several steps with render settings and materials, all to no avail.  Eventually I just pulled the thing into Poser Pro and did without the IL.

And I do mean that it just stops.  The display of the precalc stops at the top right corner somewhere, though the status message may eventually suggest that it is done, it never goes on to the rendering stage.  Repeated this behavior multiple times.