MP3 Player is currectly in use but it doesn't have any files opened

[Undead4798]

I want to eject my MP3 player but there's always the same message:

'MP3 PLAYER (E' is currently in use.
Save any open files on this disc, and then close the files or programs using the files before trying again.
If you choose to continue, the files will be closed, which might cause data to be lost.

But I didn't have any files open on that disc, no programs opened on it either and this kept happening whenever I eject it and I choose to continue with it and it messed up the disc a little whenever I use it to listen to music.
Do you know how to fix it?

 

[rgd1101]

reject from pc? could be any of the background app