When I close Lightroom and open it again, I get the error message "The Lightroom catalog named "Lightroom Catalog..." cannot be opened because another application already has it opened." I understand this is caused by failure of the lock file to be removed from the catalog folder. Dragging the lock file to the trash solves the problem... temporarily. The problem occurs every time I open Lightroom. The Lock file refuses to be automatically deleted when shutting down Lightroom. Does anyone know of a way to automatically delete the lock file when I close Lightroom? I never had this problem until after I installed the newest version of Lightroom. Thanks for any help.