I'm using VS2005 Beta2 and trying to bind a WinForm control to an entity property using Object DataSources, but I get a nasty error when I run the form. Here's my repro steps:

• Create a new Windows Application project
• Add references to my DAL, BL and the ORMSupport Classes.
• Add using lines to form1.cs for the above references
• Show the Data Sources tree (Shift+Alt+D)
• Add a new Object Data Source - picked "PersonEntity" from the EntityClasses namespace in my DAL Assembly
• Drop the "Surname" field onto form1 (creating a personEntityBindingSource, personEntityBindingNavigator, "Surname:" label and textbox.
• Run the project
• BANG! with the following error:

System.ArgumentException was unhandled
  Message="Cannot bind to the property or column Surname on the DataSource.\r\nParameter name: dataMember"
  Source="System.Windows.Forms"
  ParamName="dataMember"
  StackTrace:
       at System.Windows.Forms.BindToObject.CheckBinding()
       at System.Windows.Forms.BindToObject.SetBindingManagerBase(BindingManagerBase lManager)
       at System.Windows.Forms.Binding.SetListManager(BindingManagerBase bindingManagerBase)
       at System.Windows.Forms.ListManagerBindingsCollection.AddCore(Binding dataBinding)
       at System.Windows.Forms.BindingsCollection.Add(Binding binding)
       at System.Windows.Forms.BindingContext.UpdateBinding(BindingContext newBindingContext, Binding binding)
       at System.Windows.Forms.Control.UpdateBindings()
       at System.Windows.Forms.Control.OnBindingContextChanged(EventArgs e)
       at System.Windows.Forms.Control.OnParentBindingContextChanged(EventArgs e)
       at System.Windows.Forms.Control.OnBindingContextChanged(EventArgs e)
       at System.Windows.Forms.Control.set_BindingContextInternal(BindingContext value)
       at System.Windows.Forms.ContainerControl.set_BindingContext(BindingContext value)
       at System.Windows.Forms.ContainerControl.get_BindingContext()
       at System.Windows.Forms.Control.get_BindingContextInternal()
       at System.Windows.Forms.Control.get_BindingContext()
       at System.Windows.Forms.Control.UpdateBindings()
       at System.Windows.Forms.Control.OnBindingContextChanged(EventArgs e)
       at System.Windows.Forms.Control.OnParentBindingContextChanged(EventArgs e)
       at System.Windows.Forms.Control.OnBindingContextChanged(EventArgs e)
       at System.Windows.Forms.ContainerControl.OnCreateControl()
       at System.Windows.Forms.Form.OnCreateControl()
       at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
       at System.Windows.Forms.Control.CreateControl()
       at System.Windows.Forms.Control.WmShowWindow(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
       at System.Windows.Forms.ContainerControl.WndProc(Message& m)
       at System.Windows.Forms.Form.WmShowWindow(Message& m)
       at System.Windows.Forms.Form.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)
       at System.Windows.Forms.Control.SetVisibleCore(Boolean value)
       at System.Windows.Forms.Form.SetVisibleCore(Boolean value)
       at System.Windows.Forms.Control.set_Visible(Boolean value)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at test.Program.Main() in C:\Work\test\Program.cs:line 16
       at System.AppDomain.nExecuteAssembly(Assembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()

This is due to an issue with ICustomTypeDescriptor and .NET 2.0. (see this bug) To work around it, set the BindingSource to an instance, not a type. The designtime code sets the datasource of the bindingsource object to a type, which fails. If you set it to an instance, it works. This requires you to set the bindingsource object to a new instance of the entity.