Ok, I have found the cause of the problem : I had no sound when my instrument was NOT plugged in the SPDIF socket or if my instrument was not turned-on. (This is what it seemed to be a random bug)
Very strange, if I turned-on my instrument, I had sound and all was fine. I tried to uninstall pulseaudio but It was the same.
I have done a new fresh install from jaunty x64 beta and this problem is gone.
Anyway I still don't understand why I had no sound if nothing was plugged in the SPDIF socket. The opposite would have been more logical.
Ok, I have found the cause of the problem : I had no sound when my instrument was NOT plugged in the SPDIF socket or if my instrument was not turned-on. (This is what it seemed to be a random bug)
Very strange, if I turned-on my instrument, I had sound and all was fine. I tried to uninstall pulseaudio but It was the same.
I have done a new fresh install from jaunty x64 beta and this problem is gone.
Anyway I still don't understand why I had no sound if nothing was plugged in the SPDIF socket. The opposite would have been more logical.
Thanks