After launching a few commands :

echo autospawn = no >> ~/.config/pulse/client.conf  #use ~/.pulse/client.conf on Ubuntu <= 12.10
killall pulseaudio
$LANG=C pulseaudio -vvvv --log-time=1 > ~/pulseverbose.log 2>&1

My sound does not work. (just with the speakers, with headphones it works but I can not change the volume)

The sound icon on the top right corner does show a speaker with a single non continuous line.

I can not change the volume; it is frozen. There can be an extremely low output of the sound (I hear something but I am not sure...) It does not show a single output device that is avalaible, not even the "dummie". I have tried to reset pulseaudio, alsa, remove it, purging it, reinstalling it, without having success.

EDIT: I have tried launching pulseaudio via the terminal. It worked :D

However, I am very surprised why it does not automatically start at the start of the computer. Any ideas ? Here the console output :

W: [pulseaudio] authkey.c: Failed to open cookie file '/home/simonm/.config/pulse/cookie': No such file or directory
W: [pulseaudio] authkey.c: Failed to load authorization key '/home/simonm/.config/pulse/cookie': No such file or directory
W: [pulseaudio] authkey.c: Failed to open cookie file '/home/simonm/.pulse-cookie': No such file or directory
W: [pulseaudio] authkey.c: Failed to load authorization key '/home/simonm/.pulse-cookie': No such file or directory