Laney and RAOF just reported this bug in #debian-cli channel (happenning in trusty 14.04):

Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
GLib.MissingIntPtrCtorException: Unable to construct instance of type Banshee.Dap.Gui.DapInfoBar from native object handle. Instance of managed subclass may have been prematurely disposed.
  at GLib.ObjectManager.CreateObject (IntPtr raw) [0x00000] in <filename unknown>:0 
  at GLib.Object.GetObject (IntPtr o, Boolean owned_ref) [0x00000] in <filename unknown>:0 
  at GLib.Object.SetPropertyCallback (IntPtr handle, UInt32 property_id, GLib.Value& value, IntPtr param_spec) [0x00000] in <filename unknown>:0 
  at (wrapper native-to-managed) GLib.Object:SetPropertyCallback (intptr,uint,GLib.Value&,intptr)
  at (wrapper managed-to-native) object:wrapper_native_0x7f526dbc2df0 (intptr,uint,intptr)
  at GLib.Object.ConstructorCallback (IntPtr gtypeval, UInt32 n_construct_properties, IntPtr construct_properties) [0x00000] in <filename unknown>:0 
  at (wrapper native-to-managed) GLib.Object:ConstructorCallback (intptr,uint,intptr)
  at (wrapper managed-to-native) GLib.Object:g_object_newv (intptr,int,GLib.Object/GParameter[])
  at GLib.Object.CreateNativeObject (System.String[] names, GLib.Value[] vals) [0x00000] in <filename unknown>:0 
  at Gtk.Widget.CreateNativeObject (System.String[] names, GLib.Value[] vals) [0x00000] in <filename unknown>:0 
  at Gtk.Bin..ctor () [0x00000] in <filename unknown>:0 
  at Hyena.Widgets.RoundedFrame..ctor () [0x00000] in <filename unknown>:0 
  at Banshee.Dap.Gui.DapInfoBar..ctor (Banshee.Dap.DapSource source) [0x00000] in <filename unknown>:0 
  at Banshee.Dap.DapSource.<Initialize>m__E () [0x00000] in <filename unknown>:0 
  at Banshee.ServiceStack.Application+<Invoke>c__AnonStorey21.<>m__38 () [0x00000] in <filename unknown>:0 
  at Banshee.Gui.GtkBaseClient+<RunIdle>c__AnonStorey1D.<>m__A5 () [0x00000] in <filename unknown>:0 
  at GLib.Idle+IdleProxy.Handler () [0x00000] in <filename unknown>:0 
   at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
   at GLib.Idle+IdleProxy.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()