while connectiong to the dabase using sql server 2005 Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding is coming sometimes but the...

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 
{
    SqlConnection conn = new SqlConnection("Data Source=IBM_M3;Initial Catalog=Hospital;Persist Security Info=True;User ID=sa;Password=hhtpa");
    protected void Page_Load(object sender, EventArgs e)
    {
        
        conn.Open();//the error is coming here
        SqlDataAdapter da = new SqlDataAdapter("select * from viewData",conn);
        conn.Close();
        DataSet ds = new DataSet();
        da.Fill(ds);
        GridView1.DataSource = ds;
        GridView1.DataBind();
      

       
    }
    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {

    }
}