DB is Oracle 10g, Portal is Downloaded 2.6.1.
I found out the source of the Problem. It's because i am using my own EJB with own Hibernate Mapping Classes to write the User data.
I reduced the cache-time of the portal, so the Portal-Objects expire, and as i thougt, it works.
Is there any command to force a refresh of the Portal-Hibernate Objects, so that I don't have to reduce the cache-time in the ehcache.xml File?