[Eikinskjaldi]

Are you able to access mysql tables via phpmyadmin or a command line? This looks like your threadid index column has been deleted, but that can't be right if viewing threads works fine.

I can't recall 3.0.6 particularly clearly, but do you have any mods that would be affecting latest or subscribed threads drawn up in the usercp and the vbindex? That query seems wrong to me, like it should be:

SELECT thread.threadid, thread.forumid
FROM thread AS thread, subscribethread AS subscribethread
LEFT JOIN deletionlog AS deletionlog ON(deletionlog.primaryid = thread.threadid)
WHERE subscribethread.threadid = thread.threadid
AND type = 'thread'
AND subscribethread.userid = 1
AND thread.visible = 1
AND lastpost > 1189059102
AND deletionlog.primaryid IS NULL