Having solved that problem... I can now see that my fear about cdsMessageDataSet.Messages[iRow].msgtype not working correctly after a sort ect was well founded.

    private void OnDataGridViewCellFormat(object sender, DataGridViewCellFormattingEventArgs e)
      {
      if (this.dataGridView.Columns[e.ColumnIndex].Name == "imgType")
        {
        Assembly a = Assembly.GetExecutingAssembly();
        // get a list of resource names from the manifest
        //string[] resNames = a.GetManifestResourceNames();

        int iRow = e.RowIndex;
        if (cdsMessageDataSet.Messages[iRow].msgtype == "E")
          {
          e.Value = Bitmap.FromStream(a.GetManifestResourceStream("cdsProCS.Resources.Work.bmp")) as Bitmap;
          }
        else
          {
          e.Value = Bitmap.FromStream(a.GetManifestResourceStream("cdsProCS.Resources.PhoneCall.bmp")) as Bitmap;
          }
        }
      }

I have also tried:

DataRowView dv = cdsMessageDataSet.Messages.DefaultView[iRow];
if (dv["msgtype"].ToString() == "E")

To no avail.

Once the DataGridView is sorted, both methods point to the wrong record.

So I'm back to one of my earlier questions...

How do I access the current record in the DataSet.DataTable for the current row of a DataGridView?