AAFReport.frmRepMgr.NavButtonsUpdate C# (CSharp) Method

        private void NavButtonsUpdate()
        {
            System.IO.DirectoryInfo di = new System.IO.DirectoryInfo(m_CurrentAAFPath);
            btnBackUp.Enabled = (di.Parent != null);

            bool b_DirSelected = false;
            if (trvAAFFolder.SelectedNode != null)
            {
                String strNode = StrMinus(trvAAFFolder.SelectedNode.ToString(), "TreeNode: ");
                if (strNode.IndexOf(":\\") == 1)
                {
                    // This is a path node (current path) no navigation needed
                }
                else
                {
                    try
                    {
                        di = new System.IO.DirectoryInfo(m_CurrentAAFPath + "\\" + strNode);
                        b_DirSelected = IsViewableDirectory(di);
                    }
                    catch (System.NotSupportedException nse)
                    {
                        // Additional information: The given path's format is not supported.
                        int hc = nse.GetHashCode(); // hc is 20 or 22 for above message, other than that ??
                    }
                }
            }
            btnOpen.Enabled = b_DirSelected;
        }