I don't think it's that Keenart - I was having the same issues when I was using x32(XP).  The pic I'm working now has been a nightmare to get together :(.  I'm having to create the terrains separately & save as .vobs in order for them to retain the texture I originally put on them.

The most recent issue is prior to rendering the mat is OK - once I hit the render button the terrain quickly changes to a UV mapped rock imported from Poser and other materials decide to scale back up to 1 from where I had them.