Heads up with sound cards
Recently I had a problem with my sound on fedora. When the computer was first setup, the sound card worked. but after a while, the sound card quit working. I also had a logitech webcam connected as well. Fedora had the webcam listed as a sound card as well. By chance I discovered that the webcam was keeping the sound from working, and after removing it the sound worked fine. There was also a listing in bugzilla.redhat.com/bugzilla, so this could be caused by a variety of webcam/sound card combination.