getting exception of type 'system.outofmemoryexception' was thrown.

using System;
using System.Collections;
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;

namespace WebApplication1
{
    public partial class dob : System.Web.UI.Page
    {
        
        protected void Page_Load(object sender, EventArgs e)
        {
            
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection("Data Source=ADMIN-PC;Initial Catalog=testdb;User ID=sa;Password=Klogwiy8");
            con.Open();
            SqlCommand com = new SqlCommand("insert into dob values('"+txtName.Text+"','','"+txtDOB.Text+"')");
            com.Connection = con;
            com.ExecuteNonQuery();
            con.Close();
        }

        protected void Button2_Click(object sender, EventArgs e)
        {
            Response.Redirect("show58.aspx");
        }

        protected void Button3_Click(object sender, EventArgs e)
        {
            String Bir = txtdob2.Text;

            DateTime birth = Convert.ToDateTime(Bir);
            DateTime present = DateTime.Now;
            TimeSpan ts = birth - present;
            DateTime age = DateTime.MinValue.AddDays(ts.Days);
            Response.Write("Current age is : "+age.Year+" years " +age.Month+ " Months "+age.Day+" Days");
            if (age.Year > 58)
            {
                Response.Write("This Employee has retired");
            }
        }
    }
}