[EDIT: using a simplified test page without Javascript etc.]
I\'ve got a webpage that contains four audio files. These files are served as HTML5
Looking at generated source of your page you load as first source an ogg file then a mp3 file in this exact order
But, as specified in http://html5doctor.com/native-audio-in-the-browser/ file are in inverse order, so try to do the same
otherwise try to serve in your sources also an aac audio in a m4a/mp4 container
I was having a similar issue with files not loading and came up with this solution. It seems that HTML5 audio/video can "stall", meaning that is just stops loading. Luckily, there's a "stall" event that fires when this happens. What I did was listen for this event and when/if it fires, just try to force the audio to load again.
Example using jQuery:
// the event is 'onstalled' - 'stalled' in the jquery case
$("audio").bind("stalled", function() {
var audio = this;
audio.load();
// Threw in these two lines for good measure.
audio.play();
audio.pause();
});