...driver problems?? you might wanna describe ure problem a lil better. mtlhd's already mentioned:
You might wanta give out more info, like what kinda SoundCard you have, the version of red hat you're using. There're several issues I can think of right now that might be wrong. But just tell us what soundcard you have and version of RH. It'll be a lot easier that way.
also are mp3s the only things that wont play? do wavs, au's, or the system sounds, etc play?