Attached Link: http://www.3dmenagerie.com/index-goo.htm

heyas; if you select the polygons in the mfm, you can tell it to use inverse normals. ummm... i forget what the menu is called, but it's like slightly right of center. this option is near the bottom of the menu. i think it only works if the part you're trying to invert is one object. like if you double-click on a vertex to get all the connected mesh. if you've already welded it, i don't think you can do this. yeah, it's coming back to me now, i think it's polymesh:use reverse normals. if you turn that on, it changes to read 'use standard normals,' so you can switch it back. the funny thing is, sometimes 'standard' normals coming out of ray dream are backwards, and sometimes 'inverse' normals are. it's not predictible. actually, if you mirror the bit, tell the new half to flip normals, then weld, it might make the normals half-messed-up anyway. i THINK it has to do with the vertex order of the polygons. clockwise face out, counter-clockwise face in or some such. if you're using booleans, you're VERY brave! :) if it's only part of the model, or a few inverted polygons here and there, you can use the grouping tool to fix them. select the backwards polys, and then use the 'reverse group normals.' i think there's a tutorial on my site about using the grouper to fix abnormals, try that out.