[Sound] Problems with sound

[0p413 <opale@xxxxxxxxx>]

I hear the kde sounds or the wav files, but others program give me
problems: with KsCd I hear nothing, xmms don't let me play or add files
to playlist, mplayer says :"Can't open audio device /dev/dsp: Device or
resource busy",...
If I try to open mp3 files from Konqueror i've got a crash.

All of that happens from the first second of installation!!!
What can I do?