New Post: template with Excel5 not work

I create a new Excel file from a template. I then use:

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->setPreCalculateFormulas(false);

and it work. But if i use:

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
$objWriter->setPreCalculateFormulas(false);

the formulas disappear.
If I will not use
$objWriter->setPreCalculateFormulas(false);
the script not end never and system go in resource consumption.
How to fix?