Have you considered not making this an automated procedure? Packing and indexing is probably the most intensive thing you can do to your database files. I've always felt it should be run intentionally by a user who is responsible enough to run the pack/index and report any errors that might occur. In all of my application login routines I allow for a "manager" user who can only log in when no other users are present and upon logging in automatically disables other users during the session. This "manager" user then has exclusive access to the application and files, and certain operations like packing/indexing can only be done by this user.

- Dean