This posting helped me as well ??
I was using an older template. After upgrading from V2.0.11 to 2.6.2 the comments did not looked as the should. It seemed like wp used another comments.php than the one located in the template folder after the upgrade!
I was forced to use:
<?php comments_template('/comments.php'); ?>
in my single.php and page.php.
Why was not the correct comments.php called by:
<?php comments_template(); ?>
?