chgrp www-data -R /var/www/ilovephilosophy.com/phpbb/images/avatars/
chmod g+rw -R /var/www/ilovephilosophy.com/phpbb/images/avatars/
would be nice. The PHP script is not getting permission to write to the directory.
Nobody,
Thanks for flagging this up, I have changed the permissions to allow people to upload avatars.