What does this error mean?

They are popping up at the top of the page in the admin section and also when I submit new posts….

WordPress database error: [Can’t open file: ‘ks_comments.MYI’ (errno: 144)]
SELECT COUNT(*) FROM ks_comments WHERE comment_approved = ‘0’

WordPress database error: [Can’t open file: ‘ks_comments.MYI’ (errno: 144)]
SELECT COUNT(comment_ID) FROM ks_comments WHERE comment_approved = ‘spam’

WordPress database error: [Can’t open file: ‘ks_comments.MYI’ (errno: 144)]
DESC ks_comments

WordPress database error: [Can’t open file: ‘ks_comments.MYI’ (errno: 144)]
ALTER TABLE ks_comments ADD COLUMN comment_subscribe enum(‘Y’,’N’) NOT NULL default ‘N’

WordPress database error: [Can’t open file: ‘ks_comments.MYI’ (errno: 144)]
SELECT comment_post_ID as post_id, COUNT(comment_ID) as comment_count FROM ks_comments WHERE comment_approved=’1′ GROUP BY comment_post_ID