1. do u have a sound daemon running? in gnome, you can use esd. u need to run this as root from a terminal window:
u'll hear some sound if your card is configured properly.
2. well, i don't use mozilla when using linux. i prefer netscape. u can download it for free with the plugins (java, flash) that you need. check www.netscape.com.
if u still prefer using mozilla, i think this issue had been discussed before (or was it another plugin issue?
). try search the LQ and maybe u'll get a hit.