Then one day I should play some tracks, I could not find any. The music was gone. The folders were emtpy, only albumart left. I tried several recoveryprograms which gave me no luck. I got quite frustrated.

A thing that gave me hope was that disk usage had not changed. Weeks later I gave it a new try. I started up MediaMonkey which I thougt was the program that had deleted the files and looked at the setting. Then I discovered a rule for moving files. All files was moved to a directory for old mp3-files with less than 160kbs bitrate. This was a huge relief. But several hours have been spent creating a new folder structure and moving the files back.

I store my music files on a 2x750GB raid1. Backup of this is also being considered because of this episode.