It sounds like the options or what to do need when a mass storage device (USB) is connected needs adjusting. Sorry but I can't guess without having the machine in front of me.
Bob
This makes no sense at all.
OS: Mac OS-X 10.8.5 on Mac Mini
Camera: R42
If I shoot in AVCHD and connect via USB to the computer, press Play, I am presented with the option to connect to the computer. I affirm it and then it appears on the Desktop. All is well.
Now, let's say I have nothing but MP4 on the Camcorder. If I follow the above procedure the only thing I see on the LCD is a USB icon and nothing else. The camera will not mount and it is not visible to the O/S.
If however I have a mix of MP4 and AVCHD then I will be prompted to connect.
What this is telling me is that I must have at least one AVCHD present on the Camera in order to connect to the computer.
Thoughts anyone?

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