Sounds like you need to take ownership of your files (sounds silly, I know). If you already own the files, you'd think you wouldn't have to take ownership of them! But, sometimes that is the case.
You can do it manually by going through the Properties > Securities > Advanced > Owner > Edit > but that registry hack I found will probably do it faster.
Try selecting all your MP3's then do the "right-click take ownership" on all of them at once (to save some clicking). I cannot guarantee it will work, as I have not tried this myself.
If this does not solve your problem, you might have to manually add yourself to the list of Permissions that you saw for each file (let's hope not!).
Let me know if it works.