Audio issues on Ubuntu Linux

You may have been wondering why I would ever need to quit and restart Firefox, anyway. It's because I've been having really annoying audio issues on Ubuntu Linux: different applications fight for control of the audio device, and rarely can two apps play audio at the same time. Some apps (VLC, Java) handle this gracefully, by just not playing audio when they can't get to the device. Others (Amarok, Totem) will hang or crash. The worst offender is the non-free Flash plugin for Firefox: once it grabs the audio device (e.g. when playing a YouTube video) it never lets it go, even after the Flash app ends and the page is closed—the only way to wrest control away is to quit Firefox. Also, if it can't get control, it hangs, and even after I quit Firefox I have to kill the process (and Firefox won't even let me restart until I've killed the process).

Any Ubuntu users out there? Have you run into this problem at all? I don't think I've done anything to change the default audio setup, and I install updates for everything pretty regularly. I would like to use Gnash or some other free Flash player instead of the non-free one, but so far none of them seem up to snuff for even basic things like YouTube. And even if I did switch, other apps still don't play nice with each other, which makes me think it's something about my Ubuntu setup itself that's causing the problems. Any help would be appreciated.

Update: Partial fix found.