I have been having a problem with a SUMVISION MP3 player for some time.
I can copy the music i want from windows to my mp3 and it gets saved ok, and i can copy it back onto someone elses computer BUT when i try to play the file on my MP3 player it just comes up with the error message...... Drive Empty!
After some time trying to reformat and reflash with no sucess i have found a Fix which i am posting up here for anyone else with the same problem.
Get the windows backup file from here
and then use windows backup to restore the MP3 data.
My player was a SUMVISION M18 but this will probably work with many others.
if u want to be safe backup the mp3 BEFORE you try restoring this file to it!