Does this happen with Banshee > 1.3.0?

Yes, with 1.4.x.

I can reproduce crash by trying to open the properties dialog for one of the predefined playlists in the smart playlist dialog as well.

Ha. It doesn't crash if I don't run it in Dutch. With LC_ALL=nl_NL.UTF I get this:

uto:~ > banshee
[Info  00:25:23.144] Running Banshee 1.4.1
[Info  00:25:28.094] All services are started 4,541072s
[Info  00:25:32.356] nereid Client Started
[Warn  00:25:32.832] Caught an exception - org.freedesktop.Hal.NoSuchProperty: No property volume.is_mounted on device with id /org/freedesktop/Hal/devices/platform_floppy_0_storage_platform_floppy (in `NDesk.DBus.Proxies')
  at IDeviceProxy.GetPropertyBoolean (System.String ) [0x00000] 
  at Hal.Device.GetPropertyBoolean (System.String key) [0x00000] 
  at Banshee.HalBackend.Volume.get_IsMounted () [0x00000] 
  at Banshee.HalBackend.Volume.CheckVolumeMounted (Banshee.HalBackend.Volume volume) [0x00000] 
  at Banshee.HalBackend.Volume.Resolve (Banshee.HalBackend.BlockDevice parent, Hal.Manager manager, Hal.Device device) [0x00000] 
Marshaling clicked signal
Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object
  at Banshee.Query.Gui.RatingQueryValueEntry.set_QueryValue (Hyena.Query.QueryValue value) [0x00000] 
  at Hyena.Query.Gui.QueryTermBox.set_QueryNode (Hyena.Query.QueryTermNode value) [0x00000] 
  at Hyena.Query.Gui.QueryTermsBox.AddNode (Hyena.Query.QueryNode node) [0x00000] 
  at Hyena.Query.Gui.QueryTermsBox.set_QueryNodes (System.Collections.Generic.List`1 value) [0x00000] 
  at Hyena.Query.Gui.QueryBox.set_QueryNode (Hyena.Query.QueryNode value) [0x00000] 
  at Banshee.SmartPlaylist.Editor.set_Condition (Hyena.Query.QueryNode value) [0x00000] 
  at Banshee.SmartPlaylist.Editor.UpdateForPlaylist (Banshee.SmartPlaylist.SmartPlaylistSource playlist) [0x00000] 
  at Banshee.SmartPlaylist.Editor.HandleAdvUse (System.Object sender, System.EventArgs args) [0x00000] 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (object,object[])
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] --- End of inner exception stack trace ---

  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] 
  at System.Delegate.DynamicInvokeImpl (System.Object[] args) [0x00000] 
  at System.MulticastDelegate.DynamicInvokeImpl (System.Object[] args) [0x00000] 
  at System.Delegate.DynamicInvoke (System.Object[] args) [0x00000] 
  at GLib.Signal.ClosureInvokedCB (System.Object o, GLib.ClosureInvokedArgs args) [0x00000] 
  at GLib.SignalClosure.Invoke (GLib.ClosureInvokedArgs args) [0x00000] 
  at GLib.SignalClosure.MarshalCallback (IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data) [0x00000] 
   at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
   at GLib.SignalClosure.MarshalCallback(IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data)
   at GLib.SignalClosure.MarshalCallback(IntPtr , IntPtr , UInt32 , IntPtr , IntPtr , IntPtr )
   at Gtk.Dialog.gtk_dialog_run(IntPtr )
   at Gtk.Dialog.gtk_dialog_run(IntPtr )
   at Gtk.Dialog.Run()
   at Banshee.SmartPlaylist.Editor.Run()
   at Banshee.SmartPlaylist.Editor.RunDialog()
   at Banshee.Gui.SourceActions.OnSourceProperties(System.Object o, System.EventArgs args)
   at System.Reflection.MonoMethod.InternalInvoke(System.Object , System.Object[] )
   at System.Reflection.MonoMethod.InternalInvoke(System.Object , System.Object[] )
   at System.Reflection.MonoMethod.Invoke(System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture)
   at System.Reflection.MethodBase.Invoke(System.Object obj, System.Object[] parameters)
   at System.Delegate.DynamicInvokeImpl(System.Object[] args)
   at System.MulticastDelegate.DynamicInvokeImpl(System.Object[] args)
   at System.Delegate.DynamicInvoke(System.Object[] args)
   at GLib.Signal.ClosureInvokedCB(System.Object o, GLib.ClosureInvokedArgs args)
   at GLib.SignalClosure.Invoke(GLib.ClosureInvokedArgs args)
   at GLib.SignalClosure.MarshalCallback(IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data)
   at GLib.SignalClosure.MarshalCallback(IntPtr , IntPtr , UInt32 , IntPtr , IntPtr , IntPtr )
   at Gtk.Application.gtk_main()
   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.Reflection.Assembly , System.String[] )
   at System.AppDomain.ExecuteAssembly(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()

Marking as a duplicate of bug 581987 because its patch fixes the crash.

*** This bug has been marked as a duplicate of 581987 ***