Question How to disable ctrl+alt+del?

[Dimness]

hi.
I want to disable Ctrl+Alt+Del in windows 7, trough the registery or something (that be automatically) without premission.
I was trying the next code:

Dim key As RegistryKey = Registry.LocalMachine
        Dim subkey As RegistryKey
        Dim keyString = "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon"


        Dim regKey = "DisableCAD,0"
        My.Computer.Registry.SetValue( _
        keyString, regKey, "1", RegistryValueKind.DWord)

but the access denide, how do i bypass this?
p.s. if u can to tell me how to this on 'Fast User Switching' and disable this too it be great
thanks