Movies and Sound freezes in Firefox

[neil.linux]

I'm using Kubuntu Edgy as a clean install with all repositories (main, 
restricted, universe, multiverse) for the edgy main, edgy-backports, 
edgy-security and edgy-proposed  and the extras found using Automatix 
and Easy Ubuntu.
I'm using ALSA sound on a Intel IC5/ICH5R AC'97 Audio Controller sound card.
My video card is an ATI Radion 9200 Pro (RV280) using the ATI driver 
installed as the default.


My problem is that embedded movies streamed over the Internet freeze 
after the first 15 to 30 seconds when using Firefox 2.0 (Although the 
video still continues to download). I have no problem streaming them 
through Kaffeine except I get intermittent sound (ie sound for 15 
seconds then nothing then maybe sound again after about a minute)
.
I had the same problem with Firefox 1.5.x under Dapper.

When playing from the hard drive they play all the way through but with 
intermittent sound (see above).  This happens with both mplayer and xine 
based plugins and players.

What steps could I be doing to troubleshoot this and does anyone know of 
a workaround that might address this issue?

Many thanks in advance for any help people may be able to offer.

Neil Blenkiron
Melbourne, Australia