Sub Main()
    Dim filename As String = "C:\test.xls"
    Dim excel As New Microsoft.Office.Interop.Excel.Application()
    Try
        excel.Visible = True
        Dim pvw As Microsoft.Office.Interop.Excel.ProtectedViewWindow = _
          excel.ProtectedViewWindows.Open(filename)
        Dim wb As Microsoft.Office.Interop.Excel.Workbook = pvw.Workbook
        'Dim wb As Microsoft.Office.Interop.Excel.Workbook = CType( 
        ' excel.Workbooks.Open(filename), 
        ' Microsoft.Office.Interop.Excel.Workbook)
        Dim ws As Microsoft.Office.Interop.Excel.Worksheet = TryCast( _
          excel.ActiveSheet, Microsoft.Office.Interop.Excel.Worksheet)
    Catch ex As System.Exception
        MsgBox(ex.Message & vbLf & ex.StackTrace)
    End Try
End Sub