Audio outjack

Gonna encourage you to open up your terminal. In order to do this, on your gnome panel click acessories>terminal. Type the command "lspci" without the quotes, select the output generated pressing Ctrl+Shift+C (This copies the text result) and pasting the output lets see if we can figure out the problem.

for more information on how to solve you can refer to the link

http://ubuntuforums.org/showthread.php?t=806620