I am not certain why all the problems with motion menu backgrounds. When I edit a project (I use Edius 5.0) I will edit the entire movie - output it to the appropriate blu-ray format and then add on a 30-40 second clip (just the video usually) at the end of the timeline and output that with the same parameters as the original movie and save it for later use. Of course, elementary stream is of utmost importance. I have made over 30 blu-ray projects in the last couple of years and they all had motion menu backgrounds and motion chapter buttons and not a single problem. I have all my movies, project files and source files on the same RAID 0 drive. Be sure, though, that there is not heavy fragmentation of your source files - even on a RAID 0 drive this can cause problems and not allow the volume to be written.