<audio controls preload>
               &#060source src="iphone.ogg"&#062</source>
               Your browser does not support this
           </audio>

I've put a .ogg source in an <audio> tag like so: <audio controls preload> &#060source src="iphone.ogg"&#062</source> Your browser does not support this </audio> Following some guidance I found online, I also put a .htaccess file in the /firefoxbug folder to set the MIME types: AddType audio/ogg .oga AddType video/ogg .ogv AddType application/ogg .ogg However, it doesn't work. The console does not show any errors except: "All candidate resources failed to load. Media load paused." If you try this example from w3schools, I get a similar problem: http://www.w3schools.com/html/tryit.asp?filename=tryhtml_audio_all It doesn't work here either, and the console shows this, expectantly, for the mp3 file: "Specified 'type' attribute of 'audio/mpeg' is not supported. Load of media resource horse.mp3 failed." But here, too, there's no specific error that explains why the ogg isn't loading. It simply says, again, "All candidate resources failed to load. Media load paused." Edit: Safe mode did not help. Neither did reinstallation. I do not experience this issue with Firefox 18.0