USB transfer issues?

[Qbcade]

everytime i try to transfer videos from a usb key to my microSD card via the dock, they get corrupted. anyone had similar issues? I can play the videos directly from the usb key, but the same file after xfering to the microsd card via the laptop dock my player says that it can't open the files most times or the file will have an issue during playback. anyone had this? is this just 'broken' on the dock or ?