I upgraded 3 blogs to 2.7. Everything works fine. But with one of them, I cannot use the wp-sample-config.php file, because - after putting in the right information and some secret keys - I am redirected to the WP installation page. If I reinstall the old wp-config.php, I get the login page back again.
The error sits in the new wp-config.php file, but what can it be? Any ideas anyone?