I had been having random success in an effort to play mp3's and cd's with FC3. I had searched the recent mail list with no luck. Volume control settings that worked one day, did not the next. This morning I noticed that when Firefox was not running, that mp3's played fine in xmms but when Firefox was loaded with web sites, mp3's did not play and the sound card warning window appeared. This did not happen on just any web site but only for Yahoo sites I checked; the Gnome home page and Fedora home pages were not a problem. I disabled all the plugins, but that did not solve the problem. Any ideas on this setup issue?
I had a quick look and didn't see anything on the yahoo site that would require sound.
I've noticed similar problems in FC2, and assumed that libflashplayer was keeping a lock on the sound device.
Which is strange, since my sound card never had a problem playing multiple simultaneous sounds under RedHat 9.