Wrong behavior in Backups
This can be VSS based DPM backups. Do you also have info in the Errorlog about "I/O Frozen for database xxx" and "I/O thawed for database xxx" ? That is sign of VSS (Snapshot) backups. If you rely on that kind of backups you should (as always) ensure that you can restore the backups, and you should pay special attention to Log backups.