ran some tracing as I just got the error again, will dig out the code and find out why it has gone weird
exec sp_executesql N'SELECT COUNT(*) FROM FORUM_TOPICS t LEFT JOIN FORUM_FORUM Forum ON t.FORUM_ID = Forum.FORUM_ID LEFT JOIN FORUM_MEMBERS a ON a.MEMBER_ID = t.T_AUTHOR LEFT JOIN FORUM_MEMBERS lpa ON lpa.MEMBER_ID = t.T_LAST_POST_AUTHOR WHERE (T_STATUS < 99 OR T_AUTHOR=@0 OR T_UREPLIES>0)AND ( t.T_LAST_POST>''20171122091836'')ORDER BY T_LAST_POST DESCWHERE (t.CAT_ID IN(2,6,5,4,10,1,14,17,7,9))',N'@0 int',@0=1311
go
looks like petapoco has done something odd with the count query for paging