Videolan settings for handling mime-types

[mabel]

Hi, this is probably a real newbee question: Under Windows XP, I set VL as the default handler for a number of filetypes - that works, no problem. But now I want to change that for some files, e.g. I want WMP to open .wma files, in particular when using my webbrowser (Firefox). Using VLC, I seem not to be able to make any changes: I uncheck the box for .wma-files, click OK, but next time I look the checkmark is there again. I tried a few other extensions - same (non)result. So that's my main question: is this 'normal'?
I then tried windows explorer: it now indeed uses WMP when I doubleclick a .wma file. (Yet, in Videolan the box for wma is still checked.) Internet Explorer now uses WMP too, but there's still something strange: when IE asks whether I want to open the file, I see the Videolan icon displayed.
But my preferred browser is Firefox. It lists Videolan as the default player for .wma files (where does it get that info from, I wonder). But Firefox allows the user to choose a different, non-default, application for any filetype (or rather: for any mime-type). However, setting a preference for WMP doesn't change anything: still Videolan keeps popping up to play the .wma file...
Have others encountered similar behaviour or should I conclude that my registry is seriously compromised? (It occurs on 2 different computers, though.)

[Jean-Baptiste Kempf]

This is a firefox issue then.