Have you tried choosing the dv easy setup (the stock one, not the blackmagic one) before turning on the deck? I would choose the dv easy setup and FCP should say that it cannot find the external device. Hit ok. Hide fcp. Turn on the firewire deck, and if fcp doesn’t find it automatically, refresh devices. Also, there might be a bus conflict between your lacie and your firewire deck. You should have your lacie on a separate FW800 card (they are under $50 US).
Also, what kind of dv deck do you have? If there’s component outputs, why don’t you just run your deck through the Extreme? It might save you from all of this hassle.
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G5 Dual 2Ghz <> 4GB RAM <> FCP 5.02 <> Kona 2
ATTO 42XS <> Huge Systems 1.25 TB 4105 Fibre