No pulseaudio sound

Hello, Using Synaptic I installed pulseaudio and pavucontrol. Running the latter in a terminal produces these messages: ** (pavucontrol:4086): WARNING **: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files /usr/bin/pulseaudio: symbol lookup error: /usr/bin/pulseaudio: undefined symbol: pa_dbus_connection_unref Running Skype in a terminal also produces the second line above. Skype and the Flash player do not play any sound. And the Control Centre shows no reference to pulseaudio. Any ideas on how to make it available? Robert