Magento shows blank/empty page, I was scared when this happened on one of the live site but after some exercises with source code and using internet I come to find out the solution. Most probably it could have memory issue or the compilation tool.
In order to troubleshoot the issue, your first step is to edit index.php, find out bellow line and uncomment
If its not available, insert this line somewhere at the top of the file and try out bellow solutions.
Try – 1 : Disable Complier
Go to System -> Tools -> Compilation and Disable you Complier and clear/flush magento cache data. In most of the cases this would solve the issue.
Try – 2 : Improve PHP Memory Limit
If you can access php.ini OR using .htaccess in the root OR edit index.php add bellow line right after ini_set(‘display_errors’, 1);
Try – 3 : Design changes
If you have recently installed new theme try to switch interface to a previously used one. Flush Magento cache after each operation. Magento will switch to default theme if it can not find a custom one.
I hope these would resolve your problem.