public partial class Form1 : Form
{
  [DllImport("coredll.dll")]
    static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

  [DllImport("coredll.dll")]
  static extern IntPtr CallWindowProc(IntPtr lpPrevWndFunc, IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

  [DllImport("coredll.dll")]
  public static extern IntPtr GetWindowLong(IntPtr hWnd, int nIndex);


  //public struct tagSHCHANGENOTIFYENTRY
  //{
  //    [MarshalAs(UnmanagedType.SysUInt)]
  //    public ulong dwEventMask;

  //    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 4096)]
  //    public string WatchDir;

  //    [MarshalAs(UnmanagedType.Bool)]
  //    public bool fRecursive;
  //}
  //tagSHCHANGENOTIFYENTRY test;

  //[DllImport("aygshell.dll")]
  //static extern bool SHChangeNotifyRegister(IntPtr hwnd, ref tagSHCHANGENOTIFYENTRY test);

  const int GWL_WNDPROC = -4;

  public delegate int WindProc(IntPtr hWnd, int msg, IntPtr Wparam, IntPtr lparam);

  static private WindProc SampleProc;
  IntPtr OldDefProc = IntPtr.Zero;

  public enum SHCNE : uint
  {
      SHCNE_RENAMEITEM = 0x00000001,
      SHCNE_CREATE = 0x00000002,
      SHCNE_DELETE = 0x00000004,
      SHCNE_MKDIR = 0x00000008,
      SHCNE_RMDIR = 0x00000010,
      SHCNE_MEDIAINSERTED = 0x00000020,
      SHCNE_MEDIAREMOVED = 0x00000040,
      SHCNE_DRIVEREMOVED = 0x00000080,
      SHCNE_DRIVEADD = 0x00000100,
      SHCNE_NETSHARE = 0x00000200,
      SHCNE_NETUNSHARE = 0x00000400,
      SHCNE_ATTRIBUTES = 0x00000800,
      SHCNE_UPDATEDIR = 0x00001000,
      SHCNE_UPDATEITEM = 0x00002000,
      SHCNE_SERVERDISCONNECT = 0x00004000,
      SHCNE_UPDATEIMAGE = 0x00008000,
      SHCNE_DRIVEADDGUI = 0x00010000,
      SHCNE_RENAMEFOLDER = 0x00020000,
      SHCNE_FREESPACE = 0x00040000,
      SHCNE_EXTENDED_EVENT = 0x04000000,
      SHCNE_ASSOCCHANGED = 0x08000000,
      SHCNE_DISKEVENTS = 0x0002381F,
      SHCNE_GLOBALEVENTS = 0x0C0581E0,
      SHCNE_ALLEVENTS = 0x7FFFFFFF,
      SHCNE_INTERRUPT = 0x80000000,
  }

  public enum SHCNF
  {
      SHCNF_IDLIST = 0x0000,
      SHCNF_PATHA = 0x0001,
      SHCNF_PRINTERA = 0x0002,
      SHCNF_DWORD = 0x0003,
      SHCNF_PATHW = 0x0005,
      SHCNF_PRINTERW = 0x0006,
      SHCNF_TYPE = 0x00FF,
      SHCNF_FLUSH = 0x1000,
      SHCNF_FLUSHNOWAIT = 0x2000
  }

  public const uint WM_SHNOTIFY = 0x0401;

  private const int WM_FILECHANGEINFO = (0x8000 + 0x101);

  public struct SHChangeNotifyEntry
  {
      public IntPtr pIdl;
      [MarshalAs(UnmanagedType.Bool)]
      public Boolean Recursively;
  }



  [DllImport("coredll.dll", EntryPoint = "#2", CharSet = CharSet.Auto)]
  private static extern uint SHChangeNotifyRegister(
      IntPtr hWnd,
      SHCNF fSources,
      SHCNE fEvents,
      uint wMsg,
      int cEntries,
      ref SHChangeNotifyEntry pFsne);

  [DllImport("Ceshell.dll", CharSet = CharSet.Auto)]
  private static extern uint SHGetSpecialFolderLocation(
      IntPtr hWnd,
      CSIDL nFolder,
      out IntPtr Pidl);

  public enum CSIDL
  {
      /// <summary>
      /// Desktop
      /// </summary>
      CSIDL_DESKTOP = 0x0000,
      /// <summary>
      /// Internet Explorer (icon on desktop)
      /// </summary>
      CSIDL_INTERNET = 0x0001,
      /// <summary>
      /// Start Menu\Programs
      /// </summary>
      CSIDL_PROGRAMS = 0x0002,
      /// <summary>
      /// My Computer\Control Panel
      /// </summary>
      CSIDL_CONTROLS = 0x0003,
      /// <summary>
      /// My Computer\Printers
      /// </summary>
      CSIDL_PRINTERS = 0x0004,
      /// <summary>
      /// My Documents
      /// </summary>
      CSIDL_PERSONAL = 0x0005,
      /// <summary>
      /// user name\Favorites
      /// </summary>
      CSIDL_FAVORITES = 0x0006,
      /// <summary>
      /// Start Menu\Programs\Startup
      /// </summary>
      CSIDL_STARTUP = 0x0007,
      /// <summary>
      /// user name\Recent
      /// </summary>
      CSIDL_RECENT = 0x0008,
      /// <summary>
      /// user name\SendTo
      /// </summary>
      CSIDL_SENDTO = 0x0009,
      /// <summary>
      /// desktop\Recycle Bin
      /// </summary>
      CSIDL_BITBUCKET = 0x000a,
      /// <summary>
      /// user name\Start Menu
      /// </summary>
      CSIDL_STARTMENU = 0x000b,
      /// <summary>
      /// logical "My Documents" desktop icon
      /// </summary>
      CSIDL_MYDOCUMENTS = 0x000c,
      /// <summary>
      /// "My Music" folder
      /// </summary>
      CSIDL_MYMUSIC = 0x000d,
      /// <summary>
      /// "My Videos" folder
      /// </summary>
      CSIDL_MYVIDEO = 0x000e,
      /// <summary>
      /// user name\Desktop
      /// </summary>
      CSIDL_DESKTOPDIRECTORY = 0x0010,
      /// <summary>
      /// My Computer
      /// </summary>
      CSIDL_DRIVES = 0x0011,
      /// <summary>
      /// Network Neighborhood (My Network Places)
      /// </summary>
      CSIDL_NETWORK = 0x0012,
      /// <summary>
      /// user name>nethood
      /// </summary>
      CSIDL_NETHOOD = 0x0013,
      /// <summary>
      /// windows\fonts
      /// </summary>
      CSIDL_FONTS = 0x0014,
      CSIDL_TEMPLATES = 0x0015,
      /// <summary>
      /// All Users\Start Menu
      /// </summary>
      CSIDL_COMMON_STARTMENU = 0x0016,
      /// <summary>
      /// All Users\Start Menu\Programs
      /// </summary>
      CSIDL_COMMON_PROGRAMS = 0X0017,
      /// <summary>
      /// All Users\Startup
      /// </summary>
      CSIDL_COMMON_STARTUP = 0x0018,
      /// <summary>
      /// All Users\Desktop
      /// </summary>
      CSIDL_COMMON_DESKTOPDIRECTORY = 0x0019,
      /// <summary>
      /// user name\Application Data
      /// </summary>
      CSIDL_APPDATA = 0x001a,
      /// <summary>
      /// user name\PrintHood
      /// </summary>
      CSIDL_PRINTHOOD = 0x001b,
      /// <summary>
      /// user name\Local Settings\Applicaiton Data (non roaming)
      /// </summary>
      CSIDL_LOCAL_APPDATA = 0x001c,
      /// <summary>
      /// non localized startup
      /// </summary>
      CSIDL_ALTSTARTUP = 0x001d,
      /// <summary>
      /// non localized common startup
      /// </summary>
      CSIDL_COMMON_ALTSTARTUP = 0x001e,
      CSIDL_COMMON_FAVORITES = 0x001f,
      CSIDL_INTERNET_CACHE = 0x0020,
      CSIDL_COOKIES = 0x0021,
      CSIDL_HISTORY = 0x0022,
      /// <summary>
      /// All Users\Application Data
      /// </summary>
      CSIDL_COMMON_APPDATA = 0x0023,
      /// <summary>
      /// GetWindowsDirectory()
      /// </summary>
      CSIDL_WINDOWS = 0x0024,
      /// <summary>
      /// GetSystemDirectory()
      /// </summary>
      CSIDL_SYSTEM = 0x0025,
      /// <summary>
      /// C:\Program Files
      /// </summary>
      CSIDL_PROGRAM_FILES = 0x0026,
      /// <summary>
      /// C:\Program Files\My Pictures
      /// </summary>
      CSIDL_MYPICTURES = 0x0027,
      /// <summary>
      /// USERPROFILE
      /// </summary>
      CSIDL_PROFILE = 0x0028,
      /// <summary>
      /// x86 system directory on RISC
      /// </summary>
      CSIDL_SYSTEMX86 = 0x0029,
      /// <summary>
      /// x86 C:\Program Files on RISC
      /// </summary>
      CSIDL_PROGRAM_FILESX86 = 0x002a,
      /// <summary>
      /// C:\Program Files\Common
      /// </summary>
      CSIDL_PROGRAM_FILES_COMMON = 0x002b,
      /// <summary>
      /// x86 Program Files\Common on RISC
      /// </summary>
      CSIDL_PROGRAM_FILES_COMMONX86 = 0x002c,
      /// <summary>
      /// All Users\Templates
      /// </summary>
      CSIDL_COMMON_TEMPLATES = 0x002d,
      /// <summary>
      /// All Users\Documents
      /// </summary>
      CSIDL_COMMON_DOCUMENTS = 0x002e,
      /// <summary>
      /// All Users\Start Menu\Programs\Administrative Tools
      /// </summary>
      CSIDL_COMMON_ADMINTOOLS = 0x002f,
      /// <summary>
      /// user name\Start Menu\Programs\Administrative Tools
      /// </summary>
      CSIDL_ADMINTOOLS = 0x0030,
      /// <summary>
      /// Network and Dial-up Connections
      /// </summary>
      CSIDL_CONNECTIONS = 0x0031,
      /// <summary>
      /// All Users\My Music
      /// </summary>
      CSIDL_COMMON_MUSIC = 0x0035,
      /// <summary>
      /// All Users\My Pictures
      /// </summary>
      CSIDL_COMMON_PICTURES = 0x0036,
      /// <summary>
      /// All Users\My Video
      /// </summary>
      CSIDL_COMMON_VIDEO = 0x0037,
      /// <summary>
      /// Resource Direcotry
      /// </summary>
      CSIDL_RESOURCES = 0x0038,
      /// <summary>
      /// Localized Resource Direcotry
      /// </summary>
      CSIDL_RESOURCES_LOCALIZED = 0x0039,
      /// <summary>
      /// Links to All Users OEM specific apps
      /// </summary>
      CSIDL_COMMON_OEM_LINKS = 0x003a,
      /// <summary>
      /// USERPROFILE\Local Settings\Application Data\Microsoft\CD Burning
      /// </summary>
      CSIDL_CDBURN_AREA = 0x003b,
      /// <summary>
      /// Computers Near Me (computered from Workgroup membership)
      /// </summary>
      CSIDL_COMPUTERSNEARME = 0x003d,
      /// <summary>
      /// combine with CSIDL_ value to force folder creation in SHGetFolderPath()
      /// </summary>
      CSIDL_FLAG_CREATE = 0x8000,
      /// <summary>
      /// combine with CSIDL_ value to return an unverified folder path
      /// </summary>
      CSIDL_FLAG_DONT_VERIFY = 0x4000,
      /// <summary>
      /// combine with CSIDL_ value to insure non-alias versions of the pidl
      /// </summary>
      CSIDL_FLAG_NO_ALIAS = 0x1000,
      /// <summary>
      /// combine with CSIDL_ value to indicate per-user init (eg. upgrade)
      /// </summary>
      CSIDL_FLAG_PER_USER_INIT = 0x0800,
      /// <summary>
      /// mask for all possible 
      /// </summary>
      CSIDL_FLAG_MASK = 0xFF00,
  }

  public enum SHGetFolderLocationReturnValues : uint
  {
      /// <summary>
      /// Success
      /// </summary>
      S_OK = 0x00000000,
      /// <summary>
      /// The CSIDL in nFolder is valid but the folder does not exist
      /// </summary>
      S_FALSE = 0x00000001,
      /// <summary>
      /// The CSIDL in nFolder is not valid
      /// </summary>
      E_INVALIDARG = 0x80070057
  }

  public static IntPtr GetPidlFromFolderID(IntPtr hWnd, CSIDL Id)
  {
      IntPtr pIdl = IntPtr.Zero;
      SHGetFolderLocationReturnValues res = (SHGetFolderLocationReturnValues)
          SHGetSpecialFolderLocation(
          hWnd,
          Id,
          out pIdl);
      return (pIdl);
  }


    public Form1()
    {
        InitializeComponent();

         SampleProc = new WindProc (SubclassWndProc);

         OldDefProc = GetWindowLong(this.Handle, GWL_WNDPROC);

        SetWindowLong(this.Handle, GWL_WNDPROC, Marshal.GetFunctionPointerForDelegate(SampleProc)/*SampleProc.Method.MethodHandle.Value.ToInt32()*/);

        //tagSHCHANGENOTIFYENTRY changeentry = new tagSHCHANGENOTIFYENTRY();
        //changeentry.dwEventMask = (ulong)SHCNE.SHCNE_ALLEVENTS;
        //changeentry.fRecursive = true;
        //changeentry.WatchDir = null;

        //SHChangeNotifyRegister(this.Handle, ref changeentry);

        SHChangeNotifyEntry changeentry = new SHChangeNotifyEntry();




        changeentry.pIdl = GetPidlFromFolderID(this.Handle, CSIDL.CSIDL_DESKTOP);
        changeentry.Recursively = true;

        try
        {
            uint notifyid = SHChangeNotifyRegister(
            this.Handle,
            SHCNF.SHCNF_TYPE | SHCNF.SHCNF_IDLIST,
            SHCNE.SHCNE_ALLEVENTS,
            WM_FILECHANGEINFO,
            1, ref changeentry);


        }

        catch (Exception ee)
        {

        }

i am failing in SHChangeNotifyRegister please help me.. tell me the reason why i am crashing..same code work fine for desktop.. please help

Thanks.