I used Digital Rebellion's Pref Mgr to trash all prefs; then Compressor Repair to fix them. Rebooted. Stopped Qmaster. Reset services. Established 5 instances ( I have 8 core Xeon 2.8ghz Mac Pro ). Restarted Qmaster sharing. Opened FCP file, sent to Compressor. Selected DVD settings. Chose cluster I set up in Qmaster. Submitted. Instant "HOST Failed" error messages on the five instances that appeared in Batch Monitor.