[mskvkin]

Я немного подправил выше написанный код:

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, sButton, syncobjs, comctrls, sGroupBox;

Const
  Symbol = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

type
  TForm1 = class(TForm)
    sGroupBox1: TsGroupBox;
    Button1: TButton;
    sGroupBox2: TsGroupBox;
    Memo1: TMemo;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  tnew = class(tthread)
  private
  protected
    procedure execute; override;
  end;

var
  Form1: TForm1;
  new1, new2: tnew;

implementation

{$R *.dfm}

procedure tnew.execute;
procedure FindCombination(S: String; Level: Integer);
Var
  i: Integer;
begin
  for i := 1 to Length(Symbol) do
    begin
      Form1.Memo1.Lines.Add(S + Symbol[i]);
      if Level < Length(Symbol) then FindCombination(S + Symbol[i],Level+1);
    end;
end;
begin
  FindCombination('',0);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  new1 := tnew.create(true);
  new1.freeonterminate := true;
  new1.priority := {tphighest}tptimecritical;
  new1.resume;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  new1.Suspend;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Memo1.Lines.Clear;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  new1.Suspend;
  new1.Terminate;
end;

end.

это даст возможность выполнения одновременно нескольких действий при подборе значений