LinuxQuestions.org - phpBB/SQL Problem

Can anybody tell me why I get this error whenever I post a reply on my forum? Thanks.

Quote:

SQL Error : 1 Can't create/write to file '/root/tmp/#sqla7b_2ac_0.MYI' (Errcode: 13)

SELECT u.username, u.user_id, u.user_posts, u.user_from, u.user_website, u.user_email, u.user_icq, u.user_aim, u.user_yim, u.user_regdate, u.user_msnm, u.user_viewemail, u.user_rank, u.user_sig, u.user_sig_bbcode_uid, u.user_avatar, u.user_avatar_type, u.user_allowavatar, u.user_allowsmile, p.*, pt.post_text, pt.post_subject, pt.bbcode_uid FROM phpbb_posts p, phpbb_users u, phpbb_posts_text pt WHERE p.topic_id = 7 AND pt.post_id = p.post_id AND u.user_id = p.poster_id ORDER BY p.post_time ASC LIMIT 0, 15

Line : 393
File : /var/www/html/phpBB2/viewtopic.php