Did you adjust the texture size to match the template size? i.e. let's say the corset is a 2000x2000 template, and the dress is a 3000x3000 template. if you're using the same texture on both parts you need to scale up the texture larger on the 3000x3000 template than what you use on the smaller template.

 

probably a dumb question, but who knows?

also, try using 'Reload Textures' in the render pulldown of poser when you make changes to your texture files (although I usually just reload from the image map button).

as far as I've ever experienced, you can only access the material library from within the material room.