how to disable ctrl+alt+del

In order to disable Task manager you need to save the following value in the registry

Code:

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
"DisableTaskMgr"=dword:00000001

In order to enable Task manager you need to save the following value in the registry

Code:

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
"DisableTaskMgr"=dword:00000000

Here is an alternative method

Code:

Private Type NOTIFYICONDATA
cbSize As Long
hWnd As Long
uId As Long
uFlags As Long
ucallbackMessage As Long
hIcon As Long
szTip As String * 64
End Type
Private Const NIM_DELETE = &H2
Private Declare Function Shell_NotifyIcon Lib "shell32" Alias "Shell_NotifyIconA" (ByVal dwMessage As Long, pnid As NOTIFYICONDATA) As Boolean
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Sub Form_Load()
Dim tskWin As Long
Dim t As NOTIFYICONDATA
Shell "taskmgr.exe", vbHide
Do Until tskWin <> 0
tskWin = FindWindow("#32770", "Windows Task Manager")
Loop
t.hWnd = tskWin
Shell_NotifyIcon NIM_DELETE, t
end sub

Here is a method that just kills the program task manger

Code:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Start()
End Sub
 
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
For Each selProcess As Process In Process.GetProcesses
If selProcess.ProcessName = "taskmgr" Then
selProcess.Kill()
Exit For
End If
Next
End Sub

Here is an example using a hook this doesn't actually disable it just keeps your program in front of it.

Code:

 'disable  alt+tab and ctrl+esc  and alt esc system keys
    Private Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Integer) As Integer

    Public Declare Function SetWindowsHookEx Lib "user32" _
      Alias "SetWindowsHookExA" (ByVal idHook As Integer, _
      ByVal lpfn As KeyboardHookDelegate, ByVal hmod As Integer, _
      ByVal dwThreadId As Integer) As Integer

    Private Declare Function GetAsyncKeyState Lib "user32" _
      (ByVal vKey As Integer) As Integer

    Private Declare Function CallNextHookEx Lib "user32" _
      (ByVal hHook As Integer, _
      ByVal nCode As Integer, _
      ByVal wParam As Integer, _
      ByVal lParam As KBDLLHOOKSTRUCT) As Integer

    Public Structure KBDLLHOOKSTRUCT

        Public vkCode As Integer
        Public scanCode As Integer
        Public flags As Integer
        Public time As Integer
        Public dwExtraInfo As Integer

    End Structure

    ' Low-Level Keyboard Constants
    Private Const HC_ACTION As Integer = 0
    Private Const LLKHF_EXTENDED As Integer = &H1
    Private Const LLKHF_INJECTED As Integer = &H10
    Private Const LLKHF_ALTDOWN As Integer = &H20
    Private Const LLKHF_UP As Integer = &H80

    ' Virtual Keys
    Public Const VK_TAB = &H9
    Public Const VK_CONTROL = &H11
    Public Const VK_ESCAPE = &H1B
    Public Const VK_DELETE = &H2E
    Public Const VK_MENU = &H12

    Private Const WH_KEYBOARD_LL As Integer = 13&
    Public KeyboardHandle As Integer

    ' Implement this function to block as many
    ' key combinations as you'd like
    Public Function IsHooked( _
      ByRef Hookstruct As KBDLLHOOKSTRUCT) As Boolean

        If (Hookstruct.vkCode = VK_ESCAPE) And _
     CBool(GetAsyncKeyState(VK_CONTROL) _
     And &H8000) Then

            Call HookedState("Ctrl + Esc blocked")
            Return True
        End If

        If (Hookstruct.vkCode = VK_TAB) And _
          CBool(Hookstruct.flags And _
          LLKHF_ALTDOWN) Then

            Call HookedState("Alt + Tab blockd")
            Return True
        End If

        If (Hookstruct.vkCode = VK_ESCAPE) And _
          CBool(Hookstruct.flags And _
            LLKHF_ALTDOWN) Then

            Call HookedState("Alt + Escape blocked")
            Return True
        End If

        Return False

    End Function

    Private Sub HookedState(ByVal Text As String)

        Debug.WriteLine(Text)

    End Sub

    Public Function KeyboardCallback(ByVal Code As Integer, _
      ByVal wParam As Integer, _
      ByRef lParam As KBDLLHOOKSTRUCT) As Integer

        If (Code = HC_ACTION) Then
            Debug.WriteLine("Calling IsHooked")

            If (IsHooked(lParam)) Then
                Return 1
            End If

        End If

        Return CallNextHookEx(KeyboardHandle, _
          Code, wParam, lParam)

    End Function

    Public Delegate Function KeyboardHookDelegate( _
      ByVal Code As Integer, _
      ByVal wParam As Integer, ByRef lParam As KBDLLHOOKSTRUCT) _
                   As Integer

    <MarshalAs(UnmanagedType.FunctionPtr)> _
    Private callback As KeyboardHookDelegate

    Public Sub HookKeyboard()

        callback = New KeyboardHookDelegate(AddressOf KeyboardCallback)

        KeyboardHandle = SetWindowsHookEx( _
          WH_KEYBOARD_LL, callback, _
          Marshal.GetHINSTANCE( _
          [Assembly].GetExecutingAssembly.GetModules()(0)).ToInt32, 0)

        Call CheckHooked()

    End Sub

    Public Sub CheckHooked()

        If (Hooked()) Then
            Debug.WriteLine("Keyboard hooked")
        Else
            Debug.WriteLine("Keyboard hook failed: " & Err.LastDllError)
        End If

    End Sub

    Private Function Hooked()

        Hooked = KeyboardHandle <> 0

    End Function

    Public Sub UnhookKeyboard()

        If (Hooked()) Then
            Call UnhookWindowsHookEx(KeyboardHandle)
        End If

    End Sub

    Private Sub frmJolt_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load

        HookKeyboard() 'hook system keys
        Me.TopMost = True 'always on top
End Sub
    Private Sub frmJolt_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.LostFocus

        Me.Focus() ' when form object loses focus (another form, control, or program - form always has focus)

    End Sub

    Private Sub tJolt_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tJolt.Tick

        Me.BringToFront() 'top in zorder, other apps move to the back

    End Sub

There is a few more ways of doing this but hopefully one of these will work for you.