I have a Droid Razr Maxx HD Version 4.1.2. I can no longer copy MP3 to my Droid using the USB cable. The music files are on my computer's drive and when I try to copy one to the Droid, the Copy hangs up and won't copy. I have done this successfully months ago with no problem. I have 23 Gigs free space on my Internal Storage, Music folder. Thanks for any ideas on what could be wrong.