Disable ALT

Here' s a tool that does it: http://www.exefind.com/keytrap-P9966.html

Also, check this out for free:
http://www.codeguru.com/forum/archive/index.php/t-222304.html

I found for disable
ALT+f4  in form closing event e.Cancel = True
CTRL+ALT+DELETE
Public Sub EnableTaskManager(ByVal enable As Boolean)
        Dim HKCU As Microsoft.Win32.RegistryKey = Microsoft.Win32.Registry.CurrentUser
        Dim key As Microsoft.Win32.RegistryKey =
HKCU.CreateSubKey("Software\Microsoft\Windows\CurrentVersion\Policies\System")
        key.SetValue("DisableTaskMgr", IIf(enable, 0, 1), Microsoft.Win32.RegistryValueKind.DWord)
    End Sub

I create global hook
http://www.codeguru.com/vb/gen/vb_system/keyboard/article.php/c4831/