I've been trying out a few multimedia players the last several days and now I think SMPlayer suits my taste better. I want to make it my default media player by altering the option in System > Preferences > Preferred Applications so that it's executed everytime I press the "Media" shortcut key on my keyboard. But now pressing it brings no applications at all (i.e. it no longer works), even after setting the option back to Rhythmbox (the default). Any hints?