@bonemap
Jacques, Fred and Bonemap, I have finally determined a workaround for being unable to save the large Isadora patch while editing. It is not related to having media on two different disks, as I thought, it happens when a background video is playing while I attempt a save or during an auto-save. This was an intermittent problem accompanied with one of two error messages(see attached). If I turn off the movie player and projector associated with the background video, I can save the patch. This is very strange because I have been saving a patch while a video plays to stage since I began using Isadora 12 years ago. This problem occurred on a 2017 Mac Book Pro, 2013 Mac Pro, and 3 different PCs.
Don