Problemer med at lukke for CRTL+ALT+DEL i XP

Hej

Jeg har store problemer med at lukke for CRTL+ALT+DELETE i Windows XP.  Jeg har denne kode, men tilsyneladende virker det ikke helt.
Hvad er der at gøre ?

Declare Function SystemParametersInfo Lib "user32" Alias _
"SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, _
ByVal lpvParam As Any, ByVal fuWinIni As Long) As Long

Sub DisableCtrlAltDelete(bDisabled As Boolean)
Dim x As Long
x = SystemParametersInfo(97, bDisabled, CStr(1), 0)
End Sub

Private Sub Command2_Click()
DisableCtrlAltDelete (False)
End Sub

Private Sub Command1_Click()
DisableCtrlAltDelete (True)
End Sub


Mvh

Daniel