Заблокировать Ctrl+Alt+Del

using System.Runtime.InteropServices;
    using System.Diagnostics;
 
    public partial class Form1 : Form
    {
        [StructLayout(LayoutKind.Sequential)]
        private struct KBDLLHOOKSTRUCT
        {
            public Keys key;
            public int scanCode;
            public int flags;
            public int time;
            public IntPtr extra;
        }
        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(int id, LowLevelKeyboardProc callback, IntPtr hMod, uint dwThreadId);
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern bool UnhookWindowsHookEx(IntPtr hook);
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CallNextHookEx(IntPtr hook, int nCode, IntPtr wp, IntPtr lp);
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string name);
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern short GetAsyncKeyState(Keys key);
        private IntPtr ptrHook;
        private LowLevelKeyboardProc objKeyboardProcess;
 
 
        public Form1()
        {
            InitializeComponent();
        }
        protected override bool ProcessDialogKey(Keys keyData)
        {
            switch (keyData)
            {
                case Keys.Control:
                    return true;
                default:
                    return base.ProcessDialogKey(keyData);
            }
        }
        private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)
        {
            if (nCode >= 0)
            {
                KBDLLHOOKSTRUCT objKeyInfo = (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lp, typeof(KBDLLHOOKSTRUCT));
                if (objKeyInfo.key == Keys.RWin || objKeyInfo.key == Keys.LWin) //вот тут и блокируется WinKey {   
                    return (IntPtr)1;
            }
 
            return CallNextHookEx(ptrHook, nCode, wp, lp);
        }
 
 
        //заблакировать
        private void button1_Click(object sender, EventArgs e)
        {
            ProcessModule objCurrentModule = Process.GetCurrentProcess().MainModule;
            objKeyboardProcess = new LowLevelKeyboardProc(captureKey);
            ptrHook = SetWindowsHookEx(13, objKeyboardProcess, GetModuleHandle(objCurrentModule.ModuleName), 0);
 
        }
        //разблокировать
        private void button2_Click(object sender, EventArgs e)
        {
 
            if (ptrHook != IntPtr.Zero)
            {
                UnhookWindowsHookEx(ptrHook);
                ptrHook = IntPtr.Zero;
            }
 
        }