unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, WinProcs;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
   Dummy : integer;
begin
 Dummy := 0;
  {Disable ALT-TAB}
  SystemParametersInfo( SPI_SETFASTTASKSWITCH, 1, @Dummy, 0);
  {Disable CTRL-ALT-DEL}
  SystemParametersInfo( SPI_SCREENSAVERRUNNING, 1, @Dummy, 0);
end;

end.