Private Sub Workbook_Open()
Dim w1 As String, w2 As Workbook
Application.ScreenUpdating = False
w1 = ThisWorkbook.FullName
Set w2 = ThisWorkbook
'sauvegarde même dossier
ThisWorkbook.SaveAs w2.Path & "\Sauv " & Format(Now, "dd-mm-yy hhnnss") & ".xls"
'sauvegarde dans un autre dossier
'ThisWorkbook.SaveAs "C:\Documents and Settings\NomUtilisateur\Mes documents\xld\" & "Sauv " & Format(Now, "dd-mm-yy hhnnss") & ".xls"
Application.EnableEvents = False
Workbooks.Open w1
Application.EnableEvents = True
w2.Close
Application.ScreenUpdating = True
End Sub