I'm not sure if this is a Litespeed problem or a PHP problem, however across multiple servers of ours, we are seeing the same session ID being (attemped to be) used by two people. The second person that tries to use it obviously gets a permission denied as it's already written to /tmp under the first user. I've googled around and people say this is extremely rare, so I'm not quite sure why we're seeing it on a weekly basis across multiple servers. People have also suggested using: session.entropy_length = 512 session.entropy_file = /dev/urandom in /usr/local/lib/php.ini to help make the session file more random, but it's still occuring. Anyone run into this before?