ArgumentException was unhandled

'check for the selected item in list
       If Form7.DataGridView1.Rows.Count > 0 Then
           If Form7.DataGridView1.SelectedRows.Count > 0 Then
               Dim intStdID As Integer = Form7.DataGridView1.SelectedRows(0).Cells("pID").Value
               'open connection
               If Not cnn.State = ConnectionState.Open Then
                   cnn.Open()
               End If

               'delete data
               Dim cmd As New OleDb.OleDbCommand
               cmd.Connection = cnn
               cmd.CommandText = "DELETE FROM NTIdb WHERE pID=" & intStdID
               cmd.ExecuteNonQuery()
               'refresh data
               Me.RefreshData()

               'close connection
               cnn.Close()
           End If
       End If