Firefox default problem -

[Bob Goodwin]

I accidentally typed "VNC" when I meant "VLC" when Thunderbird asked me 
how to open a .wmv file and to make matters worse I clicked on the box 
to always do that!

Now I can't find how to undo that selection.

I know I can save the file and view it from the command line but there 
ought to be a way to undo this goof.  Does anyone know where the 
selection is stored?

Bob