After upgrade to Hardy, one of the problems I have seen is that you cannot play a youtube video and a mp3 in parallel. Not only that, even *after* the youtube video finishes, vlc will give you no audio until you close the FF tab with the video.
There is a suggestion at http://linuxowns.wordpress.com/2008/04/29/hardy-heron-sound-problems/ . I will try it out later today. There is also a bugreport : https://bugs.launchpad.net/ubuntu/+bug/202878
I am posting this to see if anyone else is seeing this too. <rant> I am considering a upgrade to gutsy. </rant>
Regards, Mohan S N