SQL acting up..

[CollateralFX]

Some of the sites on my server are experiencing SQL database problems and some aren't. It seems totally random. I try to repair the databases, but it doesn't fix them. I have restarted both sql and http multiple times and rebooted the server. But certain databases are still acting up.

And in case it helps.. here is one error.

Database error: [Got error -1 from table handler]
T DISTINCT * FROM wp_posts WHERE 1=1 AND post_date_gmt <= '2005-05-25 09:23:59' AND (post_status = "publish") GROUP BY wp_posts.ID ORDER BY post_date DESC LIMIT 0, 6