Soluzione del problema sopra descritto :

Declare Function BlockInput Lib "user32" (ByVal fBlock As Long) As Long

Private Sub Start_Blocking()
BlockInput True
.............. bla bla bla
.............. bla bla bla
.............. bla bla bla
.............. bla bla bla
.............. bla bla bla
BlockInput False
End Sub

Ciao a tutti