My iMac still works, but FireWire does not... neither the 400 nor the 800 buses recognize anything connected to them. Troubleshooting steps I have tried: Restarting the Mac Changing the configuration of FireWire devices Reapplying the latest Snow Leopard Combo Update Killing system caches with OnyX Nothing has helped. This all started when I purchased a 500GB portable G-Drive mini and attempted to connect it to my Mac. The device wasn't recognized at first, so I moved the cables around and tried again. It worked for a while... but now only works via USB.