Thanks very much to the original poster. However, I have the same symptoms as nathatanu0. Followed all the steps, but when I connect my phone after reboot, the condition is exactly the same as before the steps, namely "Could not lock the device" and all folders show zero files. When I connect the phone to a Windows machine, I can see all the files in all the folders.
Samsung Galaxy S II and Ubuntu 12.04LTS
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