Can't access the trading post

I've checked the search function and found this has happened in the past....so, what do I do? Here's the error message I get when I try to go to the trading post. Any thoughts?

Could not obtain topic information

DEBUG MODE

SQL Error 3 Error writing file '/var/tmp/MYPPSQSf' (Errcode 28)

SELECT t.li, u.username, u.user_id, u.trade, u2.username as user2, u2.user_id as id2, p.post_username, p2.post_username AS post_username2, p2.post_time FROM phpbb_topics t, phpbb_users u, phpbb_posts p, phpbb_posts p2, phpbb_users u2 WHERE t.forum_id = 25 AND t.topic_poster = u.user_id AND p.post_id = t.topic_first_post_id AND p2.post_id = t.topic_last_post_id AND u2.user_id = p2.poster_id AND t.topic_type <> 2 ORDER BY t.topic_type DESC, t.topic_last_post_id DESC LIMIT 0, 40

Line 479
File viewforum.php

We're way ahead of you ;)

http//forum.freeipodguide.com/viewforum.php?f=25

I see that.....way to be on top of it! Thanks.