WordPress redirects to wp-admin/install.php

My blog keeps redirecting to wp-admin/install.php even though it’s been installed and running for a few years. I checked the database tables and they all came out clean – as in, Check Tables in phpMyAdmin gave the status message “OK” to all tables. I tried Repair Tables in phpMyAdmin to check if it would solve my problem, but it doesn’t even though phpMyAdmin gave another “OK” message after repairing the table. I’m running WordPress 3.0.1.