I'm not totally sure if this is in Carrara, but do you have your texture mapped globally? I remember in Bryce that textures could be mapped in global or local coordinates, and that when an object moved in global coordinates, the texture map stayed behind, giving it a shifting appearance. I'm not sure if this can be done in Carrara but check it out just in case. This may be caused by procedural effects. Nebula Supernova Studios