I also have this problem with a set of wings i use, and this only occurs when you have Raytrace and AO on with Point lights in the scene, get rid of the point lights and the squares dissapear. EF FIX THIS BLOODY PROBLEM>>>> GRRRRR>>>> sorry but i would have thought a fix for this would have happened ages ago...

Getting old and still making "art" without soiling myself, now that's success.