Zero sound from firefox

[Steven Pasternak]

Hi! I installed the latest firefox from mozilla in ~/firefox and have 
all of the plugins installed (realplayer, flash, mplayer), but I can't 
get any sound from it. If I go to a site that uses a flash movie with 
sound (purevolume.com), or even the real plugin (rhapsody.com, 
weather.com), I can't get any sound even if it says it does. I have 
everything on in the volume controller; nothing is muted. I even tried 
using root, with a fresh ~/.mozilla and I STILL get nothing. Is it 
mozilla.com's firefox or something deeper? Thanks!
-Steven