[ecfisa]

Hola Metal_Kingdom.

Intenta de este modo:

Código Delphi [-]
procedure FileToTString(TS: TStrings; const aFileName: TFileName);
var
  F      : file;
  nRead  : Integer;
  Buffer : array[0..4095] of byte;
  Cadena : string;
  CadPtr : PChar;
begin
  AssignFile(F, aFileName);
  Reset(F, 1);
  TS.BeginUpdate;
  try
    repeat
      BlockRead(F, Buffer, SizeOf(Buffer), nRead);
      CadPtr := @Buffer;
      SetString(Cadena, CadPtr, nRead);
      TS.Add(Cadena);
    until nRead = 0;
  finally
    TS.EndUpdate;
  end;
  CloseFile(F);
end;

Uso:

Código Delphi [-]
...
  Memo1.Clear;
  FileToTString(Memo1.Lines, 'fichero.rar');

Saludos