Instant Comment Box

DaveExcel: Thanks, I just missed it

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column <> 1 or Target.Count > 1 Then Exit Sub
On Error Resume Next
If Target.Value = 6111 Then
    Target.AddComment ("Attention")
ElseIf Target.Comment.Text = "Attention" Then
    Target.ClearComments
End If
End Sub