รบกวนขอคำแนะนำด้วยครับ backgroundWorker ทำ multi thread แสดงข้อมูลซ้ำเป็นช่วงๆครับ (ทำไม่ได้จริงๆ)

private void btnReadDBF_Click(object sender, EventArgs e) 
{ 
... 
statusStrip1.Visible = true; 
toolStripStatusLabel1.Visible = true; 
toolStripProgressBar1.Maximum = GetTotalRecords(); 
if (!backgroundWorker1.IsBusy) 
{ 
objDD TObj = new objDD (); 
dgView.Rows.Clear(); 
backgroundWorker1.RunWorkerAsync(TObj); 
btnReadDBF.Enabled = false; 
btCancel.Enabled = true; 
} 
} 
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
{ 
objDD Obj = (objDD)e.Argument; 
OleDbDataReader reader; 
int i = 0; 
try{ 
string strQuery = "select * from " + DBF_FileName; 
cmdDBF = new OleDbCommand(strQuery, connDBF); 
connDBF.Open(); 
reader = cmdDBF.ExecuteReader(); 
if (reader.HasRows){ 
while (reader.Read()) { 
index = i; 
... 
Obj.Title = reader["title"].ToString(); 
Obj.Fname = reader["fname"].ToString(); 
Obj.Lname = reader["lname"].ToString(); 
Obj.Birthdate = reader["birthdate"].ToString(); 
Obj.Address = reader["address"].ToString(); 
Obj.Moo = reader["moo"].ToString(); 
... 
Thread.Sleep(100); 
backgroundWorker1.ReportProgress(i, Obj); 
if (backgroundWorker1.CancellationPending) 
{ 
e.Cancel = true; 
backgroundWorker1.ReportProgress(0); 
return; 
} 
i++; 
} 
connDBF.Close(); 
} 
} 
catch (Exception ex) 
{ 
MessageBox.Show(ex.Message); 
} 
} 
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) 
{ 
if (!backgroundWorker1.CancellationPending) 
{ 
objDDObj = (objDD)e.UserState; 
dgView.Rows.Add( 
... 
Obj.Title.ToString(), 
Obj.Fname.ToString(), 
Obj.Lname.ToString(), 
Obj.Birthdate.ToString(), 
Obj.Address.ToString(), 
Obj.Moo.ToString(), 
... 
); 
toolStripProgressBar1.Value = e.ProgressPercentage; 
toolStripStatusLabel1.Text = "Processing row.. " + e.ProgressPercentage.ToString() + " of " + TotalRecords; 
} 
}