[Lynne]

This is the only place I can find something like that query:

include/functions.php line 3047:
$counter_select = 'forum.forumid, lastpost, lastposter, lastthread, lastthreadid, lasticonid, threadcount, replycount, lastpostid';

It has to do with your forum cache. It gets used in another query that looks like your query on line 3067. I think I would start by reuploading the file. I would probably also do a repair/optimize on my forum table if I knew I had a backup (which I always do).

edit: very weird. Your last error said "3.6.0 Beta 2" and yest you say you are using 3.6.8. Something strange is going on.