I am getting banding in the dark areas when printing. Photoshop (CS5) cropping is causing the problem. I reproduce fine art. Before the image is cropped it prints fine (no banding). For the final print I use the crop tool to crop to the edge of the painting and tilt the crop a little to straighten the painting. I am not using perspective when cropping and I am not interpolating during the crop. It is just the most basic crop with no sizing or ppi settings. The file printed after cropping shows banding.
I have spent an entire afternoon troubleshooting the problem and making countless test prints. It is definitely being caused by the cropping tool.
Try without tilting to straighten. I do not know how that can be accomplished without some sort of interpolation. You may also want to try setting your photoshop default interpolation to other setting and try you crop and straighten process.