Odd problem here. We're getting the infamous "MySQL has gone away" problem when some (but not all) users try to register on our site, after they click Submit. The stack trace is as follows: Code: An exception occurred: Mysqli prepare error: MySQL server has gone away in /home/pcharms/public_html/library/Zend/Db/Statement/Mysqli.php on line 77 Zend_Db_Statement_Mysqli->_prepare() in Zend/Db/Statement.php at line 115 Zend_Db_Statement->__construct() in Zend/Db/Adapter/Mysqli.php at line 381 Zend_Db_Adapter_Mysqli->prepare() in Zend/Db/Adapter/Abstract.php at line 478 Zend_Db_Adapter_Abstract->query() in Zend/Db/Adapter/Abstract.php at line 808 Zend_Db_Adapter_Abstract->fetchPairs() in XenForo/Phrase.php at line 332 XenForo_Phrase::loadPhrases() in XenForo/Template/Abstract.php at line 186 XenForo_Template_Abstract->render() in XenForo/Template/Public.php at line 110 XenForo_Template_Public->render() in NodesAsTabs/NavTabs.php at line 126 NodesAsTabs_NavTabs::createNodeTabs() call_user_func_array() in XenForo/CodeEvent.php at line 90 XenForo_CodeEvent::fire() in XenForo/Dependencies/Public.php at line 491 XenForo_Dependencies_Public->_getNavigationContainerParams() in XenForo/Dependencies/Public.php at line 371 XenForo_Dependencies_Public->getEffectiveContainerParams() in XenForo/FrontController.php at line 612 XenForo_FrontController->renderView() in XenForo/FrontController.php at line 158 XenForo_FrontController->run() in /home/pcharms/public_html/index.php at line 13 Originally thinking this was load, we tried restarting the server and getting the user to register immediately afterwards with the load at minimum, with no effect. We also disabled listeners (to forcibly disable the CPU-hungry application we use and to ensure no add-on issues were causing the problem. We're on an Apache 2.4 box with MySQL 5.5, PHP 5.5, Memcached, and the Zend Opcache, if that helps any.