If a little more detail would help...
The query that's failing is:
INSERT IGNORE INTO `phpws_forums_smf`.smf_messages(`id_msg`, `id_topic`, `poster_time`, `id_member`, `subject`, `poster_name`, `poster_ip`, `id_board`, `smileys_enabled`, `body`, `poster_email`, `modified_name`, `icon`) VALUES (....<bunch of message bodies here>....) ORDER BY null
The URL this fails on is:
I've tried turning on debug mode (by adding '&debug=1' to the url) It seems to be detecting this flag (I added a line of code to check..), but doesn't ever write a debug log, or output anything different to the browser.