Open bug in launchpad.net:
https://bugs.launchpad.net/bugs/861799

"$LANGUAGE=C banshee --debug

[...]

[1 Warn 17:35:19.114] Could no read GConf key plugins.lastfm.expanded - GLib.GException: Configuration server couldn't be contacted: D-BUS error: Method "LookupExtended" with signature "ssb" on interface "org.gnome.GConf.Database" doesn't exist
 (in `gconf-sharp')
  at GConf.Client.Get (System.String key) [0x00000] in <filename unknown>:0
  at Banshee.GnomeBackend.GConfConfigurationClient.TryGet[Boolean] (System.String namespace, System.String key, System.Boolean& result) [0x00000] in <filename unknown>:0
[1 Debug 17:35:19.500] TrackInfoDisplay RenderAnimation: 16,00 FPS
Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
GLib.GException: Configuration server couldn't be contacted: D-BUS error: Method "Set" with signature "s(ib)" on interface "org.gnome.GConf.Database" doesn't exist

  at GConf.Client.SetValue (System.String key, GConf.Value val) [0x00000] in <filename unknown>:0
  at GConf.ClientBase.Set (System.String key, System.Object val) [0x00000] in <filename unknown>:0
  at Banshee.GnomeBackend.GConfConfigurationClient.Set[Boolean] (System.String namespace, System.String key, Boolean value) [0x00000] in <filename unknown>:0
  at Banshee.Configuration.ConfigurationClient.Set[Boolean] (System.String namespace, System.String key, Boolean value) [0x00000] in <filename unknown>:0
  at Banshee.Configuration.ConfigurationClient.Set[Boolean] (SchemaEntry`1 entry, Boolean value) [0x00000] in <filename unknown>:0
  at Banshee.Configuration.SchemaEntry`1[System.Boolean].Set (Boolean value) [0x00000] in <filename unknown>:0
  at Banshee.Gui.PersistentWindowController.InnerSave () [0x00000] in <filename unknown>:0
  at Banshee.Gui.PersistentWindowController.OnTimeout () [0x00000] in <filename unknown>:0
  at GLib.Timeout+TimeoutProxy.Handler () [0x00000] in <filename unknown>:0
   at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
   at GLib.Timeout+TimeoutProxy.Handler()
   at Gtk.Application.gtk_main()
   at Gtk.Application.Run()
   at Banshee.Gui.GtkBaseClient.Run()
   at Banshee.Gui.GtkBaseClient.Startup()
   at Hyena.Gui.CleanRoomStartup.Startup(Hyena.Gui.StartupInvocationHandler startup)
   at Banshee.Gui.GtkBaseClient.Startup()
   at Banshee.Gui.GtkBaseClient.Startup(System.String[] args)
   at Nereid.Client.Main(System.String[] args)
   at System.AppDomain.ExecuteAssembly(System.AppDomain , System.Reflection.Assembly , System.String[] )
   at System.AppDomain.ExecuteAssemblyInternal(System.Reflection.Assembly a, System.String[] args)
   at System.AppDomain.ExecuteAssembly(System.String assemblyFile, System.Security.Policy.Evidence assemblySecurity, System.String[] args)
   at System.AppDomain.ExecuteAssembly(System.String assemblyFile)
   at Booter.Booter.BootClient(System.String clientName)
   at Booter.Booter.Main()
Terminado (killed)"