Exchange 5.5 Mailbox backup problem

[Andronium]

I've been battling this error for a while now, and I haven't been able to find a solution yet. Using BE 8.6, Exchange 5.5 SP3. Information Store and Directory backups run fine, but when it gets to the mailbox backup, it usually makes it through all mailboxes until somewhere between "P" and "T". From that point all the way through the "Z"s, every mailbox gets an an error like below. It doesn't always start on the same mailbox though. The mailboxes backup as expected starting with "A" through wherever it dies. This happens on full and differential backups, but sometimes it happens and sometimes it doesn't. I am having a hard time figuring out some sort of a pattern for what could be causing this. Does anyone know hwo to fix this?

Directory not found. Can not backup directory ?Training01_PC [training01_pc] and its subdirectories.
Directory not found. Can not backup directory ?Training02_PC [training02_pc] and its subdirectories.
Directory not found. Can not backup directory ?Training03_PC [training03_pc] and its subdirectories.

 

[Andronium]

I think I figured out what was causing this... I was getting some scsi timeout errors, and I changed some of the scsi negotiate/disconnect settings as recommended by Veritas for troubleshooting scsi timeout errors. Not only did it get rid of the timeouts, but it also seems to have fixed this Exchange backup problem.