When it comes to the problem with usb transferring we've been talking about this one for a few months now and people online pretty much say it's either hardware issues (usb controller) or usb drive.. Their answer to the problem is to use Rsync or the GUI version gadmin-rsync or grsync to copy files so it has a progress bar and you'll know exactly what's going on since the CP and MV commands are a bit too basic.