Fong:

a. SD is the user preference files containing all the common setup for each user. Its a good idea to back them up.
b. Even with just users in GridView, I believe the backup will fail.
c. If the OE and AR computers were shut down then they should not show as active users.

I would recommend rebooting the server to clear all of the open files.

DataCare should only be run when all users are out of Adagio.