I do a weekend full backup that covers the System States on three servers.
Two are domain controllers, and one is a member server - all are W2K. The
primary domain controller is the one that gives me the issue. One week, all
System States will back up. The next week, all System States back up except
for the primary domain controller's. The error message is always the same:

An error occured retrieving System State files. The System State files could
not be backed up.

It's almost an every-other-week type of pattern.

Any idea what would cause the primary domain controller's System State to
be accessible one week, and not the next?

(PS: The BE service is running on the other domain controller besides the
primary.)