Re: Apple ProRes 422 file extension

This has nothing to do with FCP and everything to do with OSX. Leopard reduced (although not completely eliminated) the requirement of extensions on all files. It's beginning to use logs to identify files instead of extensions. Different versions of 10.5 will have different extension requirements and to make things even more confusing, it isn't the same across the board. 10.5.3 will have different requirements than 10.5.2.

As you have figured out, you'll just have to find a workaround