If you post up your error messages I will see if I can help you.
The files are probably .tex files which is renderman's default texture format. So what you're saying is it can't find the files? you can use Slim to check the files, there is a box you can use in the shader window to show you the texture file and if it doesn't exist it will tell you. You could always use slim scripting to go through all the texture file attributes on the shaders and tell you which ones don't exist.
A
Technical Director - Framestore
Currently working on: Your Highness
IMDB