C# 禁用ctrl+alt+del

using System;
using System.Runtime.InteropServices;
using System.Threading;
namespace LockWindows
{


/// <summary>
/// NativeWIN32 的摘要说明。
/// </summary>
public class NativeWIN32
{
   public NativeWIN32()
   {
    //
    // TODO: 在此处添加构造函数逻辑
    //
   }
  
   [DllImport("user32.dll", CharSet=CharSet.Auto)]
   public static extern IntPtr FindWindowEx(IntPtr parent /*HWND*/, 
    IntPtr next /*HWND*/, 
    IntPtr sClassName, 
    string sWindowTitle);
   [DllImport("user32.dll", CharSet=CharSet.Auto)]
   public static extern void SetForegroundWindow(int hwnd);

   [DllImport("user32.dll")]
   public static extern bool ShowWindow(int hWnd, nCmdShow nCmdShow);

   [DllImport("user32.dll", CharSet=CharSet.Auto)]
   public static extern int SendMessage(IntPtr hWnd, int msg, int wParam, int lParam);

   [DllImport("user32.dll", CharSet=CharSet.Auto)]
   public static extern int CreateMutex(IntPtr hWnd, int msg, int wParam, int lParam);

   [DllImport("HK_KeyBoardCtr.dll", CharSet=CharSet.Auto)]
   private static extern void hideHotKey();

   [DllImport("HK_KeyBoardCtr.dll", CharSet=CharSet.Auto)]
   private static extern void showHotKey();

   public static bool hideSysKey(bool bHide)
   {
    try
    {
     if(bHide)
     {
      hideHotKey();
     }
     else
     {
      showHotKey();
     }
     return true;
    }
    catch
    {
     return false;
    }
   }
   //SendMessage(Handle2, WM_GETTEXT, 1024, Integer(@Buf));

   /// <summary>
   /// 找窗口
   /// </summary>
   /// <param name="windowTittle">窗口标题</param>
   /// <returns>返回真表示找到了,返回为假表示未找到</returns>
   public static bool FindThisWindow(string windowTittle)
   {
    IntPtr hParent = IntPtr.Zero;
    IntPtr hNext=IntPtr.Zero;
    hNext=NativeWIN32.FindWindowEx(hParent,hNext,IntPtr.Zero,windowTittle);
    if(hNext.ToInt32()>0)
    {
     NativeWIN32.SetForegroundWindow(hNext.ToInt32());    
     return true;  
    }
    else
    {
     return false;
    }
   }
   public static bool isExists(string strMutex)
   {

    bool createdNew;
    System.Threading.Mutex mutex = new System.Threading.Mutex(true,strMutex,out createdNew);
    return !createdNew; //createNew为真,则表示mutex创建成功,没有冲突,这样就认为本程序没有启动
   }

   public static bool CloseTheWindows(string strWindowName)
   {
    try
    {
     IntPtr hParent = IntPtr.Zero;
     IntPtr hNext=IntPtr.Zero;
     hNext=NativeWIN32.FindWindowEx(hParent,hNext,IntPtr.Zero,strWindowName);
     if(hNext.ToInt32()>0)
     {
      //关闭窗口
      NativeWIN32.SendMessage(hNext,16,0,0);
      return true;  
     }
     else
     {
      return false;
     }
    }
    catch(Exception err)
    {
     return false;
    }
   }

   public enum nCmdShow:uint
   {
    SW_FORCEMINIMIZE=0x0,
    SW_HIDE=0x1,
    SW_MAXIMIZE=0x2,
    SW_MINIMIZE=0x3,
    SW_RESTORE=0x4,
    SW_SHOW=0x5,
    SW_SHOWDEFAULT=0x6,
    SW_SHOWMAXIMIZED=0x7,
    SW_SHOWMINIMIZED=0x8,
    SW_SHOWMINNOACTIVE=0x9,
    SW_SHOWNA=0xA,
    SW_SHOWNOACTIVATE=0xB,
    SW_SHOWNORMAL=0xC,
    WM_CLOSE=0x10,
    //    WM_GETTEXT=0x11,
   }
}
}