Dim PreviousValue

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Value <> PreviousValue Then
Sheets("log").Cells(65000, 1).End(xlUp).Offset(1, 0).Value = _
Application.UserName & " changed cell " & Target.Address _
& " from " & PreviousValue & " to " & Target.Value
End If
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
PreviousValue = Target.Value
End Sub

Private Sub Worksheet_Change2(ByVal Target As Range)