Private frmLogin As frm_Login

                If frmLogin Is Nothing OrElse frmLogin.IsDisposed Then      
                    frmLogin = New frm_Login
                End If
 
                If Not frmLogin.Visible Then
                    If frmLogin.ShowDlg() = True Then Application.Exit()
                    frmLogin.Close()
                    frmLogin.Dispose()
                    frmLogin = Nothing
                End If