nautilus open mp3

[Philip Axer]

Hi,
since some weeks I noticed an annoying problem with nautilus, running an 
up to date dapper.
Double clicking on a mp3 file should open it with xmms, that's my 
setting. But when I want listen to some music nautilus says:

"Der Dateiname »apes.mp3« deutet darauf hin, dass der Typ dieser Datei 
»mp3-Dokument« ist. Dem Dateiinhalt zu Folge handelt es sich jedoch um 
den Typen »MP3-Audio«. Daher könnte das Öffnen dieser Datei ein 
Sicherheitsrisiko für Ihr System darstellen."

short english translation:
apes.mp3 could not be opened cause the file type indicates 
"mp3-Document". The content is of the type "MP3-Audio". This could be a 
security issue.

Where is these link betweed extension and mime type stored, and how to 
change it.
I don't filed a bug, because a friend of mine, running dapper too, 
hasn't this problem.

Philip