Quote - Have you tried scaling the thing up (100 times or more). Do these stripes still appear?

*I just tried that. The stripes fade as the building gets larger. The downside is trying to maneuver in Poser with something that large. (100,000 scale)

It has something to do with absolute values and relative values. Poser scale is pretty small and sometimes self shadowing (shadow bias) comes in the way when distances are too small. Shadow bias is an absolute value (measurement) like displacement and bump map values. By increasing the scale those absolute values do not interfere anymore with the relative values of the scaling (distances in the object).

Sometime you have this problem with eyelashess in a figure where the distances are so small that the shadow bias needs to be small (to see the shadow), but that interferes with the selfshadowing of the model causing artifacts. By scaling the entire model up you bypass that problem