There's a bug fix in P13. Probably 2 or 3 releases back that addresses and issue with lights not being saved properly. This is probably fallout from that as the original issue was that all three of the light's color channels were read from and stored to the green channel. We never encountered any crashes from testing but this is the only real change to lighting I can think of for P13.

If you delete the lights before messing with render settings does that prevent the crash?

Also try saving the lights in the scene as a light set then deleting and reloading from the light set. That should correct the lights state in Poser.