No hackers and ocomment.php doesn’t exist.
I was setting up a fresh install on a new site from http://svn.automattic.com/wordpress/trunk/ using subversion.
It’s just a typo in admin-functions.php that added an o to a reference to comments.php
I ran into the same thing recently.
Edit wp-admin\admin-functions.php and search for “ocomment.php” and you’ll find one instance which needs to be changed to “comment.php” Once you’ve saved that change on your site, deleting will work again.
