public partial class Form1 : Form
{
	SqlConnection Conn;
	SqlCommand Cmd;
	SqlDataAdapter DA;
	DataSet DS;
	public Form1()
	{
		InitializeComponent();
		Conn = new SqlConnection("моя строка подключения");
		Conn.Open();
		Cmd = new SqlCommand("exec dbo.sp_myQuery @BegTime, @EndTime", Conn);
		Cmd.Parameters.Clear();
		Cmd.Parameters.Add("@BegTime", SqlDbType.DateTime);
		Cmd.Parameters.Add("@EndTime", SqlDbType.DateTime);
		Cmd.Parameters["@BegTime"].Value = new DateTime(2015,11,1,0,0,0);     //2015-11-01 00:00:00
		Cmd.Parameters["@EndTime"].Value = new DateTime(2015,12,30,23,59,59); //2015-11-30 23:59:59
		Cmd.Connection = Conn;
	}
	private void btnStart_Click(object sender, EventArgs e)
	{
		timer1.Start();
		backgroundWorker1.RunWorkerAsync();
	}
	private void timer1_Tick(object sender, EventArgs e)
	{
		//.........................
		DA = new SqlDataAdapter("select * from #Log order by [id] desc", Conn);
		DS = new DataSet();
		DA.Fill(DS, "log");  //здесь возникает ошибка Internal connection fatal error
		dataGridView1.AutoGenerateColumns = true;
		C.DataSource = DS;
		dataGridView1.DataMember = "log";
		//.........................
	}
	private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
	{
		Cmd.ExecuteNonQuery();
	}
	private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
	{
		timer1.Stop();
	}
}