I would like to be able to click on a link to a mp3 file in a web browser and select the option to either save the file or open it in the program of my choice. This has always been the expected behaviour until recently.

Now whenever I click on an mp3 file, the web browser opens it in an unidentified built-in media player.

Browsers - problem exists with firefox, chromium and opera.
Distro/Desktop Env - Have found this in OpenSuse 12.2 with Xfce and in Mint 12 with Mate

No plugins are enabled. All media players and browser plugins I could find have been uninstalled, except VLC player (not plugin) which is what I want to use to open the mp3. Browser preferences are ignored. Changing File manager preferences has no effect. I am unable to find any desktop settings which might change the problem.

Has anybody else found this a problem and fixed it?

It's expected HTML5 behaviour. Your options are to either right-click instead of left-clicking on the MP3 file, or (possibly) look for an "addon" that will give you the behaviour you're used to.

In Linux Mint I uninstalled libtotem0 (and dependencies) and gecko-mediaplayer to get the desired behaviour.

Still can't find a solution for firefox on OpenSuse

Thanks dugan, I will see if I can find a suitable add-on

For Firefox :
Edit -> Preferences -> Applications
mp3 -> set here save file in the dropdown.
It worked for me

If file starts playing in firefox, you can click on File -> save as,
it saves the mp3 file on your desired location.
.

Edit -> Preferences -> Applications Icon

You have a handler for the media type. You can uninstall the handler or change the browser to behave your way. Or go old school and right mouse -> view source and wget the mp3 URL.

or terminal >

Browser preferences are ignored for mp3

Edit -> Preferences -> Applications mp3 ... Always ask ... Save File ... Open with VLC ....

Changes nothing. All ignored. MP3 are still opened in the mystery built in player.

exo-preferred-applications is not available as a terminal command

Right-click will require extensive user training - we have 100+ people using this system.

In Opera, it's Preferences-->Advanced-->Downloads-->[Select File Type]->Edit, then select the desired application.

http://help.opera.com/Linux/9.52/en/downloads.html

I have used this to disable internal players and it works.