I was suffering from the same problem that many are ... seeing these messages when you run 4images:
Fatal error: session_start(): Failed to initialize storage module: user (path: /tmp) in
/your_home_directory/path_to_4images_gallery/includes/sessions.php on line 84
I was surprised to see that despite the large number of people who are reporting this, the answer in these forums is consistently "contact your hosting company". If anyone in these forums ever tried to give any real help with this issue, it is buried so deep in the results of the message search that nobody will ever find the answer. And if you followed that advice, the likely answer would be "contact 4Images" anyway!
If you are getting this message *CONSISTENTLY*, then there is clearly something wrong with the hosting company's server setup, and you need to ask them to take a look. Hopefully, they will fix it.
But, if 4Images works fine most of the time, and you sometimes see one of these messages, or your server seems to get hung up on them for a minute or so, then it starts working again ... try this:
Create a "/tmp/sessions" directory in your home directory, check the permission to make sure it is writeable, then add the following line to ".htaccess":
php_value session.save_path /your_home_directory/tmp/sessions
This solved my problem 100%, and I assume it will work for many of you, too. This simply isolates your 4Images session variables to a private /tmp space, avoiding whatever conflicts were causing the problem.