I get this message when I click on some links in the blog. Just a white page with this text:
Fatal error: Call to undefined function: preg_match() in /homepages/23/d222793841/htdocs/libraries/joomla/application/application.php on line 386
When I back up a page then click the link again, it usually loads fine. Just an FYI. Not sure if it's my end or your end.