It would be very helpful if the dialog box that notifies you that a different LOD is being accessed in another file would give you an indication of what file needs to be closed.
Even better, stop checking the other file status. IREALLY DO NOT CARE WHAT IS HAPPENING IN THE OHTER FILES, ESPECIALLY WHAT IS SUPPRESSED OR UNSUPRESSED IN THEM.
See the attached dialog box. It should tell you which file is stopping me from moving forward.