I’m a big fan of Plone, as little as I understand and can use it. I’ve tried a number of small CMF or Plone add-ins with varying success. Without question, the EPOZ editor offers some of the most powerful opportunities for an organization that needs to roll out a content management system to people who know nothing of HTML. One of the most common installation problems appears to be this Invalid_Ids error. Check out this excellent and easy solution at Zettai.net. It helped me greatly and, although I’ve still got “issues” to work out, Epoz works without a problem.