Hello.
First of all, thank to you who want to help me.
That's what I know about my build-in soundcard :
VIA8251, ALC655
I can have more informations if needed through an Ubuntu live cd, so, you can ask me further informations.
Now, my problem: I currently have the sound working, for all system sound (i mean, when I empty the trash, i hear the sound, for exemple); but when i try to listen an audio flux (music, movie, …), the sound is working for one second. Furthermore, after that, I have to reboot in order to get the system sound again.
I know this problem may have been solved already, but I didn't find where.
Thank you in advance =)