I noticed that FUDforum behaves strangely. I upgraded 2.7.6 to 2.7.6RC1 on http://phpmybittorrent.com/forum which is powered by SourceForge.net. I experienced the same error before upgrade.
When I try to connect for the first time in a session to the Forum I get an SQL error.
The error message is
Fatal error: SQL Error has occurred, please contact the administrator of the forum and have them review the forum's SQL query log in /tmp/persistent/phpmybittorrent/Forumdata/include/core.inc on line 189
The error log entry is
) 1064: 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 1
Query: UPDATE fud26_ses SET sys_id='38c001cc17b4929fcce24873d9b6c398', forum_id=0, time_sec=1158016199, action='Browsing the <a href=\"index.php?t=index\">forum list</a>', returnto='' WHERE id=
Server Version: 4.1.21-standard
What can I do about that? Refreshing the error page makes forum work fine.