1) If the errors are "Notice:" ... do not panic. disable notices. Tutorial link below
http://softmarket.ro/joomla-tips/how-to-turn-off-notices-in-a-joomla-driven-site-joomla-1.0-and-joomla-1.5.html
2) Check on ftp if this file has write rights. If unsure set them to 777
components/com_articleman/config/config.php

3) Do you use another WYSIWYG editor besides TinyMCE ? Try using Tiny, and tell us if that makes a difference

4) Restrictions do not work - Do not set all your users as EDITORS! in this way all can edit their content with joomla standard article manager. Users should be "registered"