This problem bedeviled us for almost two weeks now, and now that I've found the cause, hopefully I can spare some lucky soul the pain and agony of all the troubleshooting we went through here. Here's our setup: Interplay 1.2.1 ISIS 1.4 Symphony 1.8.1/Adrenaline 2.8.1 2 separate Interplay/ISIS clusters, visible to each other Our media management