Code:
Private Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
Private Const EWX_POWEROFF = &H8
Private Const EWX_FORCE = 4

Private Sub Command1_Click()
    ExitWindowsEx EWX_POWEROFF Or EWX_FORCE, 0
End Sub