I’ve uploaded an HTML5 presentation to my web server, but the playback is very unreliable.  Usually the first half will play correctly, but about halfway through, the audio stops playing and a gray “Loading…” overlay appears.  The project is then effectively dead in the water with futher audio problems even on a refresh. What causes the Loading overlay?  My audio files are under 1MB in size and there’s no reasonable lag in my network connection.