Private Function IsUserNameSet() As Boolean
        Dim CurrentUserName As String = Environment.UserName
        Return Not (CurrentUserName Is Nothing OrElse CurrentUserName.Length < 1)
    End Function
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
        If Not IsUserNameSet() Then
            '// nobody is logged in
        Else
            '// Environment.UserName / %USERNAME% is logged in
        End If
    End Sub