procedure TForm1.Button1Click(Sender: TObject);
var
  w1: Word;
  p1, p2: array[0..100] of Char;
begin
  StrPcopy(p1, 'CALC');
  if GetModuleHandle(p1) = 0 then
  begin
    StrPcopy(p2, 'C:\windows\Calc.exe');
    w1 := WinExec(p2, SW_Restore);
  end;
end;