descligar win
ExitWindowsEx(EWX_FORCE+EWX_SHUTDOWN,0) 


Printer.Title := 'Nome do relatório';


var OldValue: LongBool;

begin
// Liga a trava
SystemParametersInfo(97, Word(True), @OldValue, 0);
// Desliga a trava
SystemParametersInfo(97, Word(False), @OldValue, 0);
end;



OVI: TOSVersionInfo;

function WinVerString(I: byte): String;
begin case OVI.dwPlatformID of
VER_PLATFORM_WIN32_WINDOWS: Result := 'Windows 95';
VER_PLATFORM_WIN32_NT: Result := 'Windows NT';
else
Result := 'Unknown';
end;
if I = 1 then
Result := Format('Versão %d.%.2d', [OVI.dwMajorVersion, OVI.dwMinorVersion]);
if I = 2 then
Result := Format('%s', [Result]);
end;



// Para desabilitar os atalhos.
procedure TForm1.Button1Click(Sender: TObject);
var
Dummy: Integer;
begin
SystemParametersInfo( SPI_SETFASTTASKSWITCH, 1, @Dummy, 0);
SystemParametersInfo( SPI_SCREENSAVERRUNNING, 1, @Dummy, 0);
end;



//Para habilitar os atalhos.
procedure TForm1.Button2Click(Sender: TObject);
var
Dummy: Integer;
begin
SystemParametersInfo( SPI_SETFASTTASKSWITCH, 0, @Dummy, 0);
SystemParametersInfo( SPI_SCREENSAVERRUNNING, 0, @Dummy, 0);
end;





procedure TForm1.Button1Click(Sender: TObject);
begin
{Desabilita o botão Iniciar}
EnableWindow(FindWindowEx(FindWindow('Shell_TrayWnd', nil),
0,'Button',nil),false);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
{Habilita o botão Iniciar}
EnableWindow(FindWindowEx(FindWindow('Shell_TrayWnd', nil),
0,'Button',nil),true);
end;




Para habilitar e desabilitar a barra de tarefas do windows
use as seguintes procedures:

procedure hideTaskbar; // DESABILITA
var wndHandle : THandle;
wndClass : array[0..50] of Char;
begin
StrPCopy(@wndClass[0], 'Shell_TrayWnd');
wndHandle:= FindWindow(@wndClass[0], nil);
ShowWindow(wndHandle, SW_HIDE); // This hides the taskbar
end;

procedure showTaskbar; // HABILITA
var wndHandle : THandle;
wndClass : array[0..50] of Char;
begin
StrPCopy(@wndClass[0], 'Shell_TrayWnd');
wndHandle:= FindWindow(@wndClass[0], nil);
ShowWindow(wndHandle, SW_RESTORE); // This restores the taskbar
end; 
