I've projected a texture to a poly surface that has a joint setup to bend it (It's a book opening and im trying to texture the cover). It looks fine when the book is entirely open or closed but the half that is animated gets texture stretched during the bending animation. Whats the deal?
The problem is that you have projected the texture. Projecting a texture turns it into a three-dimensional texture which your object can 'swim' through. Imagine actually using a projector in the real world to display an image on a screen. If you move the screen while keeping the projector still, the image on the screen will move and warp. That's what's happening to your texture.
You need to create some good UV mapping for your object (should be easy for a book) and use those UVs to map your texture instead of projecting it. Check your manuals for information about UV sets and poly texturing.