Strange behavior – html in post

Hi, one of our members is experiencing problems in posting comments in Bbpress forums for buddypress: appearance of html code when pasting text coming from an external document or editor.

The text is pasted in the visual editor box (the toolbars of which btw are only accessible once the visual tab is clicked) without code. Once the post is submitted, the code appears.

http://ww.wp.xz.cn/extend/plugins/ckeditor-for-wordpress/