CS1009: Unrecognized escape sequence

I have created a site with the following connection string.

I am getting the following error message any help would be really appreciated.

Compiler Error Message: CS1009: Unrecognized escape sequence
Line 21: ad.DataFile = "D:\Hosting\9372580\html\pearl\Pearl.mdb";

my codes:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.OleDb;

public partial class html_Show_Projinfo : System.Web.UI.Page
{
    OleDbCommand cmd;
    OleDbConnection con = new OleDbConnection();
    OleDbDataReader rd;
    protected void Page_Load(object sender, EventArgs e)
    {
        int id = Convert.ToInt32(Request.QueryString["id"]);
        con.ConnectionString = ConfigurationManager.ConnectionStrings["pearl"].ToString();
        cmd = new OleDbCommand("Select * from Pearl_Projects where ProjectId=" + id, con);
        con.Open();
        rd = cmd.ExecuteReader();
        string ns;
        while (rd.Read())
        {
            Label2.Text = rd["ProjectName"].ToString();
            ns = rd["Shortdes"].ToString();
            if (ns.Length > 541)
            {
                Label1.Text = ns.Substring(0, 541);
            }
            else
            {
                Label1.Text = ns.Substring(0, ns.Length);
            }            

            Label3.Text = rd["Description"].ToString();
            Label4.Text = rd["location"].ToString();
        }
        rd.Close();
        con.Close();

        //con.Open();
        //cmd = new OleDbCommand("Select ProjectId from Pearl_ProjectDetails where DetailId=" + id, con);
        //int j = Convert.ToInt32(cmd.ExecuteScalar());
        //con.Close();

        //con.Open();
        //cmd = new OleDbCommand("Select ProjectName from Pearl_Projects