I have good news on the BrightStor topic! We finally figured out why the backups were failing on the W2K station, and now we have apparently corrected it. I have gotten two good backups so far, and at some point next week we will declare the subject resolved if all goes well! Turns out the problem was twofold - First, the unix server connects to the w2k server and sometimes loses the socket connection- they have a special switch for the agent to allow it to re-connect on a different port if the first one fails, so we turned that on and got better results, but still failures a large part of the time.
The second problem was that the port it tried to reconnect on by default was being used intermittently by another server to transmit data. We changed the port range that the agent uses to reconnect, and surprise - backups work now. I certainly hope this is the final solution. It only took 8 months and 6 or so techs to figure this out.