Compressor 3.01 problem w/ QuickCluster

I set up an 8core Mac Pro as a QuickCluster with 8 instances (1 per core) and sent a batch of .motn (Motion) files to encode to DV NTSC QTs. Everything goes thru Compressor fine but the output QT files have brief frames where it looks like some of the layers of the Composition go missing, creating odd flashes of layer dropout.

This problem only occurs when rendering via QuickCluster. If I send the same batch to "This Computer" rather than the QuickCluster name, then all renders are okay. The bummer is that QuickCluster is about 300% faster.

Has anyone had the same problem?