I got the following message from DreamHost support:
I've temporarily disabled your database because you are running a query that is hitting the database too hard.
Please prevent the following query from running:
SELECT alas_posts.*, MAX(comment_date) AS max_comment_date FROM
alas_comments, alas_posts WHERE alas_posts.post_date <= '2005-07-19
13:38:31' AND ( alas_posts.post_status = 'publish' OR
alas_posts.post_status = 'sticky' ) AND alas_posts.post_password = '' AND
alas_posts.ID = alas_comments.comment_post_ID AND
alas_comments.comment_approved = '1' GROUP BY alas_posts.ID ORDER BY
max_comment_date DESC LIMIT 0, 20;
Once you have done that, please contact support, informing them that you have disabled that query, and they will reenable your database. Please refer them to this message.
Here's the problem: I haven't the slightest clue what they're talking about or how to shut a particular query off. If I've been runing that query, I haven't been doing it on purpose.
Clearly, Dreamhost doesn't like something about my WordPress blog, but I don't understand what to change, or even how I can change anything when they've shut off my access to WordPress completely.
If anyone has encountered this problem before or has suggestions, I'd really appreciate advice. Thanks!