http://www.yolinux.com/TUTORIALS/Lin...iguration.html
Try this for mozilla. Also, if you use a soundfont enabled soundcard, check to see if your .sf2 files are loaded. MIDI should work fine in firefox. I had similar problems with midi. Also, if you use QSynth, you need to configure it to load and initiate MIDI at startup. The easiest method for this is to install QSynth, Jack, and QJackCrtl. Qsynth uses Jack to play midi. Jack is the server for the sound playback (needs to be running not just loaded) and QJackCtrl is a nice graphical way to patch you midi to alsa. I believe there is a way to setup an auto loadfing script to automate the process at boot, but I have never tried to.
Hope this helps
