[JRD!]

Juste modify CurStepChanged section on UltraArc module:

procedure CurStepChanged(CurStep: TSetupStep);
begin
   if (CurStep = ssInstall) and FileExists(ExpandConstant('{src}\records.ini')) then
     UltraARC_Process;

//   if (CurStep=ssPostInstall) and ISDoneError then begin
//      MemoIsdoneList.clear;
//       MemoExecute:='Scanning files...' + #13#10 +
//       'Rolling back changes...' + #13#10 +
//        'Error!';
//          MemoIsdoneList.Lines.Add(MemoExecute);
//         UnBtn.Enabled:=False;
//        Exec2(ExpandConstant('{uninstallexe}'), '/VERYSILENT', false);
//      DelTree(ExpandConstant('{app}'), True, True, True);
//   end;

end;

That answer your question?