SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.3.6): Invalid SQL: INSERT INTO bb1_sessions (sessionhash,userid,ipaddress,useragent,lastactivity,request_uri,styleid,langid,authentificationcode, zone) VALUES ('31e3b464514bb8a50e4e7a5a9feac402','0','38.107.191.99','CCBot/1.0 (+http://www.commoncrawl.org/bot.html)','1283851219','thread.php','0','0','', 'F')
mysql error: Duplicate entry '31e3b464514bb8a50e4e7a5a9feac402' for key 'PRIMARY'
mysql error number: 1062
mysql version: 5.1.47
php version: 5.3.2
Date: 07.09.2010 @ 11:20
Script: /schwangerschaft-f24/werdende-muetter-2011-t43604/2/
Referer: