errcode: 30 help

I’ve had my wordpress 1.5 running for some time now I get up this morning, check it, its all fine. Then a couple hours later I get this error

WordPress database error: [Can’t create/write to file ‘/tmp/#sql_49e_0.MYI’ (Errcode: 30)]
SELECT DISTINCT * FROM b2_posts WHERE 1=1 AND post_date_gmt <= ‘2005-03-26 18:23:59’ AND (post_status = “publish”) GROUP BY b2_posts.ID ORDER BY post_date DESC LIMIT 0, 10

I have saved all my posts into text documents, re-installled everything. Then it works fine you see the default post and comment. Then when I goto either make a page or post after I publish it then I get that. Help?