Two periodic errors on my site...

[MrAndrew]

Hi to all! This is my problem...

From time to time, i have hard server loads, after that two errors:

Bad SQL Query: SELECT *
              FROM 5images_users
              WHERE user_id = 
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 3

Bad SQL Query: DELETE FROM 5images_sessions
            WHERE session_id = '95ec5bc07eb8ce7a2522d70ae76cc352' OR session_user_id = 
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 2

What file need to observe?

Thanks!

[V@no]

These error come from includes/sessions.php

Are both these errors show at the same time?

[MrAndrew]

Actually, this errors comes, when searchbots, send many requests to the site. But maybe, i was mistaked! I`ve attached my sessions.php to reply...