I have a Galaxy Nexus with an unlocked bootloader, and I plan on rooting and installing a custom ROM. I was making a backup of files on my virtual SD card, but not all of them would copy to my computer. Sometimes individual files are skipped, while other times complete folders don't copy over. Overall, only about 558 MB of my 1.44 GB are transferring. I've made backups before and everything has worked - what might be going on?