Dim dt As DataTable = CType(dvKontakte.Table, DataTable)
        Dim r As DataRow
        For Each r In dt.Rows
            If r.RowState = DataRowState.Deleted Then
            Else
                r("Datum") = DateTime.Parse(r("Datum")).ToString("dd.MM.yyyy" & _
                  "HH:mm")
            End If
        Next

        lbKontakte.DataSource = dvKontakte
        lbKontakte.DisplayMember = "Datum"
        lbKontakte.ValueMember = "IDKontakt"

If it was hard to code, it should be hard to read too.