Getting Fatal error sometimes

Hi i am getting Fatal error on my site easyfriends.com

The error is on almost every pages including the admin section. The error will disappear sometime after refreshing the page. Here is the error.

 Fatal error: Call to undefined function error_reporting() in index.php on line 6

index.php will change when page changes.

Please help. Thank you

error_reporting is internal PHP function, it is always exists.

I would suggest to check if sever isn't running out of memory, it looks like it maybe related that some build-in php functions can became undefined when server is running out of memory.