Audio quits playing

I have a (mostly) successful podcast system working with the audio and playlist modules. However, the audio often just quits playing after a minute or two. I *think* I've determined that if I use the popup player the audio plays reliably whereas clicking the "triangle" button is when it won't play all the way through.

This is on 4.7 version of the modules, MySql 4.0.x, PHP 4.4.1, Firefox 1.5.x.

Also, is there a size limit on the audio file?

gil