Re: bb_get_user needs a numeric ID
Did you modify any of your template files to call any of your plugins? Sounds like a template file is referencing a plugin that no longer exists.
Let’s see, which of these require a modification to the template:
NO: allow-images.php
?: bb-avatar.php
NO: comment_QT_4_bbpress.php
NO: fix-bbpress.php
NO: js_quicktags.js
Maybe the bb-avatar plugin required a change to a template and that is causing trouble now?