title: Excel 2016 crashed when vba use saveas method on new application
body: <p>I try to use Workbook.SaveAs method to save a new workbook with a specific name. I found it runs fine within the Application which the code run on. But caused excel crash with a new application. What's the problem?
  Excel 2016 on Windows 10 Pro.
  Codes below:</p>
  
  <pre><code>Sub test()
      Dim this_app As Application
      Set this_app = Application
      Dim new_app As Application
      Set new_app = New Application
      new_app.Visible = True
      Dim wb As Workbook
      Set wb = this_app.Workbooks.Add
      wb.SaveAs Filename:="new_file_name1"
  'above SaveAs succeed
      Set wb = new_app.Workbooks.Add
      wb.SaveAs Filename:="new_file_name2"
  'above SaveAs cause excel crash
  End Sub
  </code></pre>
  
  <p>If I use <code>SaveCopyAs</code> method (code below), both is fine. But I still want to know why <code>SaveAs</code> caused Excel crashed.</p>
  
  <pre><code>Sub test()
      Dim this_app As Application
      Set this_app = Application
      Dim new_app As Application
      Set new_app = New Application
      new_app.Visible = True
      Dim wb As Workbook
      Set wb = this_app.Workbooks.Add
      wb.SaveCopyAs Filename:="new_file_name1.xlsx"
  'above SaveCopyAs succeed
      Set wb = new_app.Workbooks.Add
      wb.SaveCopyAs Filename:="new_file_name2.xlsx"
  'above SaveCopyAs also succeed
  End Sub
  </code></pre>