Attached Link: http://www.keindesign.de/stefan/poser/firefaq.html

Have you checked to make sure there were no "stray nodes" with things plugged in? I don't know how this kind of thing would happen in rendering if there isn't a node causing it, but you might be able to find an answer at the website attached. Unless this is an extension of the "smooth polygons" glitch...? Try rendering without the "smooth polygons" option checked and see what happens.