Without knowing your full environment, I can only hazard a guess. I would look at your backup program. Perhaps it is trying to back up the log and mail box files (you should not back these files up). They are always open and being written to, and even a backup program using the Domino API will have problems getting clean backups. If you require a backup of the log, you can keep it in the schedule, but corruption is a possibility. There is no reason or need to backup mailbox files.
This was first published in April 2003