Nothing fancy, I meant just what you did: objOutlookMsg.Display(False).

I just created a quick VSTO 2005 SE addin in VB as a test and had no
problems displaying the email message. I didn't get fancy and try to do
ribbon things, I just displayed a Windows.Form on startup with a "Click Me"
button that when clicked displays the email message. It worked with no
exceptions and I didn't put any error handling my little test.

Here's the code for the test I ran:

' ************ ThisAddin Class code

Imports Forms = System.Windows.Forms

public class ThisAddIn

   Private Sub ThisAddIn_Startup(ByVal sender As Object, _
       ByVal e As System.EventArgs) Handles Me.Startup

       Dim newForm As New MyForm
       newForm.Show()

   End Sub

   Private Sub ThisAddIn_Shutdown(ByVal sender As Object, _
       ByVal e As System.EventArgs) Handles Me.Shutdown

   End Sub

End class

' ************ Now the form code, unchanged from example

Imports Outlook = Microsoft.Office.Interop.Outlook

Public Class MyForm
   Private Sub Button1_Click(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles Button1.Click

       Dim objOutlook As Outlook.Application
       Dim objOutlookMsg As Outlook.MailItem
       Dim objOutlookRecip As Outlook.Recipient

       objOutlook = Globals.ThisAddIn.Application

       objOutlookMsg = objOutlook.CreateItem(Outlook.OlItemType.olMailItem)

       objOutlookRecip = objOutlookMsg.Recipients.Add("test@test.de")
       objOutlookRecip.Type = Outlook.OlMailRecipientType.olTo
       objOutlookRecip.Resolve()
       objOutlookMsg.Display()
       Me.Close()
   End Sub

End Class