Comment 18 for bug 1320020

Having similar problems with a Toshiba NB200. As a point of interest here is when the problem started.
Installed 14.04 from scratch. Did the updates. Installed Gnome Flashback. Sound working perfectly at this stage, even after several log outs.
Installed 'libtiff4' via the archives as it was needed to install Canon printerdrivers for MG4200 series. Sound still working at htis stage.
Log out. Still getting sound when switching between accounts which are chosen at log in screen.
Log in, and now no sound.
Insert headphones and notice playback device in 'Sound Settings' changes to headphones, and sound can be heard.
Unplug headphones and device changes back to speakers, and voila ......... sound through the speakers until I log off.
Log back in, and only way to get sound working is to plug, then unplug headphones.

Could this be a fault in initialisation of the sound on a user account? ie. defaulting to headphones