Всем привет.

Буквально только что, форум начал очень медленно грузится, или вообще падать.

Заглянул в erors.log nginx'а и увидел файл размером 2гб  Практически весь error.log был забит этим 

PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /
2015/12/08 21:15:52 [error] 29272#0: *80 FastCGI sent in stderr: "e 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.ru/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.ru/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.ru/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.ru/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.ru/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/Definiti
2015/12/08 21:15:52 [error] 29272#0: *80 FastCGI sent in stderr: "resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir
2015/12/08 21:15:52 [error] 29272#0: *80 FastCGI sent in stderr: "rifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57
PHP message: PHP Warning:  readdir() expects parameter 1 to be resource, boolean given in /var/www/site.com/forum/ips_kernel/HTMLPurifier/HTMLPurifier/DefinitionCache/Serializer.php on line 57

При отправке сообщения/создании темы, запрос идет очень долго и в итоге ничего не происходит. Даже 500 ошибки нет. Просто останавливается загрузка.

Что это за беда и как с ней бороться? 

Прикрепил файл с логами. В оригинале миллион строк и все они повторяются. 

Что можно с этим сделать? 

log.log