hey.. thanks for the information on those files
I switched from one user to mine and played Amarok.It said xine could not initialize audio drivers.No other application was running at that time apart from Pidgin.Then I checked if others could play any sound but they couldn't.
I could not even open System->Preferences->Sound.
Then a restart solved that.
I didn't check pavucontrol. I'll do that and report here with the details the next time it happens.