job is failing suddenly with error E0008488

[dirkdigs]

bkupexec version 12.5 with latest uodates.

server is 2003 sbs version (exchange 2003 sp1)

Error E0008488

Media Label: IMG000486

GRT backup set folder: Q:\Backup\IMG000486

V-79-57344-33928 - Access Denied. Cannot backup directory  and its subdirectories.

Job ended: August 11, 2011 at 11:48:57 PM

Completed status: Failed

Final error: 0xe0008488 - Access is denied.

Final error category: Security Errors

For additional information regarding this error refer to link V-79-57344-33928

can you help?

[ZeRoC00L]

On what files/folders or application (exchange, system state) do you receive this error ?
And what if you run the backup again, does the error occur again ?

[dirkdigs]

system state.

[pkh]

Is this the only DC in your domain?  If not, is the other DC's down during the backup?