Hi Mark, I got a good answer from AppleCare. The iMac has 2 firewire ports, but they share the same bus. It simply cannot keep up. The project plays fine on the iMac because the priority is reading in data. Trying to pump out data at the same time to the Canopus convertor, or a DV camera simply will not work. The "headscratcher" was that it worked over a network. In other words, if the firewire drive is hooked up to iMac A and the converter is hooked up to iMac B, it works fine even though it is working over a network. Why? Because the firewire bus is NOT being shared. So the way this will work is if the project I am working on is on the main iMac drive, or I can use the network. Or I can buy a Mac tower (drool)! BTW my iMac has 768 RAM, iMovie 3.0.2, system 10.2.5. Thanks for you input. Bob