Problem opening some windows selection

When I try to open some windows sellecion (with the arrow button ) a server error occurs . HOWEVER In other works well and the corresponding popup it appears .
The remaining works perfectly .
I checked the file permissions and well .

Most likely permissions.

SOLUTION
El problema es un Bug de la librería memcache que aborta la conexión con apache2, por un fallo en el protocolo de comunicación. El log del error es este:

php-cgi: libmemcached/storage.cc:341: memcached_return_t memcached_send_ascii(memcached_st*, memcached_server_write_instance_st, const char*, size_t, const char*, size_t, time_t, uint32_t,$
[Tue May 26 11:12:56 2015] [error] mod_fcgid: process /var/www/php-fcgi-scripts/web45/.php-fcgi-starter(32724) exit(communication error), get unexpected signal 6

Y ya lo hemos solucionado indicando al memcache que la comunicación sea en binario y no ASCII. El cliente puede comprobar el correcto funcionamiento del CRM.

(Referencias.:http://linux.die.net/man/1/memcached)
(http://stackoverflow.com/questions/16067307/weird-memcached-issue-with-apache)