Official comment
Yikes.
Hmm, I would recommend contacting the official tech support channel via the support ticket system.
Before you do that, I guess my only suggestion would be to put the device back into USB storage mode, and empty your computer's trash...sometimes the files are hiding in a special trash section of a USB disk, and aren't actually deleted.
If that doesn't work, please contact technical support. I 'm sorry you're experiencing this frustrating problem!
Thanks,
Rhythm Droid