There seems to be something with the defense system if you disable it and restart firefox the sound will work.
Just finished testing on 6 FF test boxes - no errors at all. All produced sound. 2 boxes uninstalled and reinstalled FF with identical results - all produced sound.
Not sure why this is not a more well know problem
Maybe because only 2 people have reported it??
The Problem is playing any media in firefox has no sound!
When you say "media", do you mean a media file called from within the web page code displayed in the browser or an application generated sound (like Outlooks "received mail" tones)?
Hope to hear a real fix for this problem I just don't have a lot of time to track down the setting or what is going on myself right now!
Funnily, I have less time and I'm still here looking for an answer. Feel free to jump in and contribute to the solution.
By the way all seem to get reset when the product updates itself also!
Take a minute and have a deeper look under the MISCELLANEOUS tab. You can export and import configs. It can maintain several configs at a time (admittedly only one at a time can be active), but this is ideal if you have a laptop and go to several locations/LANS and require different configs for different locations. This import/export facility can be used before and after an update.