Charles - finally got mine to work after playing around for a while. Most of the problem was in the mixer settings. Follow the instructions on this page
to upgrade your ALSA install from the FC2 default. After you do that, go to your mixer and check the box for advanced options. You should see a box for digital out (or something like that) - make sure it's enabled. Adjust all your volume levels to ~50 - 75% and make sure that the slider called AC97 (or some variation of that - sorry, I'm not at my machine) is muted. I did this and haven't had any problems since!