error 28 in mysql

I’ve installed WP and had it running fine until this morning. Here is the error message that’s puzzling me :
SQL/DB Error:
[Got error 28 from table handler]
SELECT DISTINCT * FROM wp_posts WHERE 1=1 AND post_date <= ‘2004-01-13 09:51:35’ AND (post_status = “publish” OR post_author = 2 AND post_status != ‘draft’) ORDER BY post_date DESC LIMIT 0,20
What I’ve read indicates that error 28 is a “lack of space” error. I have plenty of space left with my hosting company.
Thanks for your help.
B.