WordPress Database Errors

The following errors are showing up suddenly on the blog and in the control panel. It clearly has something to do with “wp_comments.MYI” and “errno: 144” but we’re just not sure what to do or where to begin. Any help we could get would be greatly appreciated.

Blog message:

WordPress database error: [Can’t open file: ‘wp_comments.MYI’. (errno: 144)]
SELECT * FROM wp_comments WHERE comment_post_ID = ’14’ AND comment_approved = ‘1’ ORDER BY comment_date

Control panel messages:

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

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