While (i = dgv.Rows.GetNextRow(0, DataGridViewElementStates.Visible))
            If (dgv.Rows(i).Cells("fehlende Daten").Value = "0") Then
                dgv.Rows.Remove(dgv.Rows(i))
            End If
        End While

For Each dr As DataGridViewRow In dgv.Rows
            If (dr.Cells("fehlende Daten").Value = "0") Then
                'dgv.Rows.Remove(dr)
                dr.DefaultCellStyle.BackColor = Color.Red
                dgv.Rows.RemoveAt(dr.Index)
            End If
        Next

For i As Integer = 0 To dgv.Rows.Count ...