Today i glad that my Firefox working and nicely play Radio streaming from my favourite sites ( www.surfmusic.de ). Also, it's solving error while playing sound / video in Firefox that throw me "The gxine plugin has crashed". Here are how to play audio, flash, radio streaming and video in Firefox Ubuntu Natty 11.04 :
I assume you already install several media player like VLC, Totem, Xine-plugin, xine.
Go to synaptic and search with keyword " mozilla " in description & name mode :