Marreco,

Set up the sheet with this code (before protecting it):

[vba]Sub sheetSetUp()
Cells.Locked = False
Columns(1).Locked = True
End Sub[/vba]
Then use this in the sheet code container:
[vba]Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 2 Then
ActiveSheet.Unprotect Password:="password"
Cells(Target.Row, 1).Value = Date
ActiveSheet.Protect Password:="password"
End If
End Sub[/vba]