I am having the Master template problem described by Apple below:
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Issue
On computers running Mac OS X 10.5 Leopard, Master Templates (templates created in Motion) do not display in Final Cut Pro 6. If you open a Master Template in Final Cut Pro, it may appear in the Viewer and the Canvas as blank or black on a computer with Leopard.
Products affected
Mac OS X 10.5 Leopard
Final Cut Pro 6
Solution
This issue is addressed by updating to Motion 3.0.2 and Final Cut Pro 6.0.2.
Choose Software Update from the Apple menu to get the latest updates for your Final Cut Studio software, or go to Apple Downloads.
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But I have done all that and still having the same problem. In fact after much frustration I reinstalled FCP, and have now installed the latest FCP update so now I am running Motion 3.0.2 and Final Cut Pro 6.0.4 but still no joy. I am running a 2.4 GHz Mac Book Pro with Leopard 10.5.4. Anyone have any suggestions?