I doubt if they are causing the problem, but deleting the cached renders might bring a further question if you didn't realize they were also temp files. So exporting any that you want before deleting all temp files is a good idea. It used to be that temp files were mostly the detritus left after a crash, so deleting them on sight was a good idea. As for the background color... do you have the SR1 installed? Are you clicking on the sphere next to the working window which controls the background color? Are you using the dots to save the UI? Carolly