Changing DataGridViewRow Properties in Another Thread

for (int i = 0; i < dgItemMaster.Rows.Count; i++)
{
  if (dgItemMaster.Rows[i].DataBoundItem.GetType().Name == "Package")
  {
   dgItemMaster.Rows[i].DefaultCellStyle.BackColor = Color.PowderBlue;
  }
}

void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            dgItemMaster.DataSource = products;
            dgItemMaster.BeginInvoke((Action)(() =>
            {
                for (int i = 0; i < dgItemMaster.Rows.Count; i++)
                {
                    if (dgItemMaster.Rows[i].DataBoundItem.GetType().Name == "Package")
                    {
                        dgItemMaster.Rows[i].DefaultCellStyle.BackColor = Color.PowderBlue;
                    }
                    else if (dgItemMaster.Rows[i].DataBoundItem.GetType().Name == "PackageKit")
                    {
                        dgItemMaster.Rows[i].DefaultCellStyle.BackColor = Color.Pink;
                    }
                }
            }));
        }

int startIndex = 0;
        Action action = null;
        action = () =>
        {   // only processes a batch of 50 rows, then calls BeginInvoke
            // to schedule the next batch
            int endIndex = startIndex + 50;
            if (endIndex > dgItemMaster.Rows.Count) endIndex = dgItemMaster.Rows.Count;

            if (startIndex > endIndex)
            {
                for (int i = startIndex; i < endIndex; i++)
                {
                    // process row i
                }

                startIndex = endIndex;
                this.BeginInvoke(action); // next iteration
            }
        };

        // kick it off
        this.BeginInvoke(action);