Error with Symantec Backup – “.sis file not found”

Hi all,
Error with Symantec Backup – “.sis file not found” I keep getting an error from one of our remote sites. Using Windows 2003 and Backup application is Symantec Backup Exec 12.
Error:
Backup – E: Data and the files could not be accessed. Previously error was located in the "SIS Store" folder, so I took that from the two drives and used the disk defrags, from that point on it is showing the above errors.
From what I can tell “.sis” files are created during and deleted after the backup process has been completed, for some reason backup is trying to recreate files that don´t exist.
