[opencms-dev] Error: not possible to get the String value...

[Binhierund at habmalnefrage.de]

Hi!
I want to try out OpenCMS and therefore I installed version 8.0.4 according to the installation instructions at http://www.opencms.org/en/development/installation/server.html on a tomcat / mysql server running on my computer. Since I don't want to develop a template first, I chose to install the default demo templates and modules. The installation worked fine, I can also login and view the demo pages. However, I'm having problems creating new content. After creating an article (v8article) or a news item (v8news) and viewing it (published or unpublished), I get the error message "It's not possible to get the String value of a nested XML content definition." Also, after creating a Dev Demo article (ddarticle), it displays a page in a rather minimalistic template and says the template was not configured correctly.

I'm wondering what is wrong. Can I not create content that way or is there an installation error? I tried reinstalling it, but still get this error message.
Thanks in advance!
Joel