This is very weird. 

I was trying out an old character I bought from DAZ ages ago, and then decided to try the same character but using a newer skin I bought recently with SSS. The end result was a skin that totally ignored the IBL. So, she looked like some sort of alien! :)

So, thinking it was the lights, I changed them around and it just got worse. Even with pointing the back lights onto the face, I was getting all sorts of those black render spots around her mouth. 

I deleted her and then started over from scratch, avoiding the old texture and all is fine. I think the old texture rendered fine with the application of EZSkin 2.0, but I could never get the new skin to replace the old nodes. 

Does anyone know what might have happened? Do pz2 mat files not replace the node structure completely? That was the impression I always had. 

Is the new character skin designed to fit the old figure? That is to say, the V3 figure cannot wear V4 textures and visaversa.

Smith Micro would no doubt tell you that MAT poses are not a supported feature, and never have been, despite e-frontier distributing some with Poser 5. ;) It's not impossible that a MAT pose is unable to properly 'root out' some node structure that was present in the previous material, and in that case starting from scratch is the simplest work-around. That combination wouldn't have been tested for, anyway.

I do occasionally find hiccups with MAT poses myself. Sometimes, applying them while you're in the material room seems to make things work better, but I haven't tested the phenomenon thoroughly.  

I think it was just a poser glitch. I tried, but I never could make it happy again, even trying to do the same steps as I had done before. I did save the original character thinking restarting poser would help, and it would load with the same behavior. But, starting with a new V4, and applying the characters in the same order worked like it was expected. 

I will say, I tend to leave poser up for weeks at a time, though, I think this time it had only been up a day or two due to computer restarts. And, as for correct figures, yeah, they were both MATs intended for V4 (which was the character I was applying them to). 

I restart Poser every time I switch to a new scene file, for precisely this reason. ;-)

I haven't had much trouble from MAT poses recently, except that hair sometimes disappears from preview after applying a MAT. It renders fine, though, and is back again next time I open the scene, so no big deal. I think it may be something to do with it having a preview mode which is different from the rest of the scene.