Reproduction -> I setup a material with normal map. Start the interactive rendering, change the normal map intensity value, swap R/G channels or just turn it off and on. Stop interactive rendering, after that it asks do you want to stop current rendering ? Whether i click yes or no c4d freezes. By the way normal map destroys the whole material when i make ANY adjustment on it, so i have to reload the whole scene, simple automatic refreshing doesnt work for that.
Thanks, Lev