I am so close to shoving something thru this screen

I have started with the bump map for one of my materials. Each time I change the bumpmap file texture I have to restart Maya to get that texture to take affect. Hitting the reload button reloads the texture but for the life of me I can't figure out why mental ray is not picking it up. It is almost as if mental ray is caching render info somewhere and just merrily ignoring the new texture. I have tried breaking the bump connection and reattaching it. I've turned off everything that looks remotely like geometry caching in the mental ray render optimization settings but nothing, nada, zip.

Any ideas?