Dim GiàSelezionato As ListViewItem

       Private Sub ListView1_ItemChecked(sender As System.Object, e As System.Windows.Forms.ItemCheckEventArgs) Handles ListView1.ItemCheck

        If Me.ListView1.CheckedItems.Count > 0 Then
            GiàSelezionato = Me.ListView1.CheckedItems(0)
        End If

    End Sub

    Private Sub ListView1_ItemChecked(sender As System.Object, e As System.Windows.Forms.ItemCheckedEventArgs) Handles ListView1.ItemChecked
        If Me.ListView1.CheckedItems.Count > 1 Then
            GiàSelezionato.Checked = False
        End If
    End Sub