How Do I prevent User, Locking the System...............?

[Appyks]

How Do I prevent User from Locking the System?

Obviously I can set following Windows registry value
But it doesn’t serve my propose
[HKEY_CURRENT_US ER\Software\Mic rosoft\Windows\ CurrentVersion\ Policies\System]
"DisableLockWor kstation"=dword :00000001

I need something as the code follows in here

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            SystemEvents.SessionSwitch += new SessionSwitchEventHandler(SystemEvents_SessionSwitch);
        }

        void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
        {
            try
            {
                if (e.Reason == SessionSwitchReason.SessionLock)
                {
                    if (MessageBox.Show("Are you sure you want to lock", "Confirm", MessageBoxButtons.YesNo) == DialogResult.No  )
                    {
                        //?????
                        //Stop the User in here…
                        //?????
                    }
                }

            }
            catch (Exception)
            {
                throw new NotImplementedException();    
            }
            
        }
    }
}

Thank you