Du kommst hier nicht rein

    Private Sub Button2_Click(sender As System.Object, _
      e As System.EventArgs) Handles button2.Click
 
        Dim di As IO.DirectoryInfo = New System.IO.DirectoryInfo("C:\users\")
        Dim node As TreeNode = treeview1.Nodes.Add(di.Name)
 
        FillNode2(node, di)
 
        MessageBox.Show("Ich bin fertig!")
 
    End Sub
 
 
    Private Sub FillNode2(ByVal node As TreeNode, _
         ByVal DirectoryName As System.IO.DirectoryInfo)
 
        Dim subnode As TreeNode = Nothing
        Dim subdir As IO.DirectoryInfo
 
        Try
            For Each subdir In DirectoryName.GetDirectories
                Try
                    subnode = node.Nodes.Add(subdir.Name)
                    subnode.ForeColor = Color.Green
                    FillNode2(subnode, subdir)
                Catch
                    subnode.ForeColor = Color.Red
                End Try
            Next subdir
        Catch ex As Exception
            node.ForeColor = Color.Red
        End Try
    End Sub