Downloading big files fails

if(function_exists('apache_get_modules')){
			$modules = apache_get_modules();
			if (is_array($modules) && count($modules) && in_array('mod_xsendfile', $modules)) {
				// If mod_xsendfile is loaded, use X-Sendfile to deliver...
				header("Expires: 0");
				header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
				header('Content-Type: application/octet-stream');
				header('Content-Disposition: attachment; filename="' . $name . '"');
				header("Cache-Control: maxage=1");
				header("Pragma: public");
				header("Content-Transfer-Encoding: binary");
				header('X-Sendfile: ' . $filename);
				$dispatcher->trigger( 'onAfterDownloadFile', array( &$filename, &$file) );
				exit;
			}
		}

$name = (strstr($_SERVER['HTTP_USER_AGENT'], 'MSIE')) ?
						preg_replace('/\./', '%2e', $fileinfo['basename'], substr_count($fileinfo['basename'], '.') - 1) :
						$fileinfo['basename'];