New user & installation problems

Hello all. I'm a new xwiki user (and I'll hope to stay a happy xwiki user). I wanted to install XWiki on my postgresql database. It was not as easy as I was thinking (but I managed to do it indeed). XWiki runs on my Tomcat 5.5.11 installation rather well, but I've got the following message in my catalina.out logfile: 20:32:43,236 WARN TP-Processor28 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'skin' 20:32:43,248 WARN TP-Processor20 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'skin' 20:32:43,272 WARN TP-Processor20 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'skin' 20:32:43,309 WARN TP-Processor28 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'skin' 20:32:43,455 WARN TP-Processor20 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'skin' Well it works, I don't really mind but wonder how can this be resolved. More anoying, those messages: 20:59:04,424 WARN TP-Processor9 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'login' 20:59:04,657 WARN TP-Processor9 RequestUtils:createActionForm:177 - No FormBeanConfig found under 'view' ... 20:59:05,633 ERROR TP-Processor9 http://zorel.org/xwiki/bin/view/Main/WebHome AssertionFailure:<init>:22 - an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session) org.hibernate.AssertionFailure: possible nonthreadsafe access to session at org.hibernate.action.EntityDeleteAction.execute(EntityDeleteAction.java:68) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:223) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141) ... com.xpn.xwiki.XWikiException: Error number 3213 in 3: Exception while deleting object XWiki.Admin Wrapped Exception: possible nonthreadsafe access to session at com.xpn.xwiki.store.XWikiHibernateStore.deleteXWikiCollection(XWikiHibernateStore.java:986) at com.xpn.xwiki.stats.impl.XWikiStatsServiceImpl.notify(XWikiStatsServiceImpl.java:209) at com.xpn.xwiki.notify.XWikiActionRule.verify(XWikiActionRule.java:51) ... Wrapped Exception: org.hibernate.AssertionFailure: possible nonthreadsafe access to session at org.hibernate.action.EntityDeleteAction.execute(EntityDeleteAction.java:68) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239) ... 20:59:08,673 WARN Finalizer JDBCContext:finalize:333 - afterTransactionCompletion() was never called This message arise when I lon on (the logon works, I'm authenticated). I'm using jdk1.5.0, tomcat 5.5.11 and XWiki Version 0.9.840. It seems to come from a misconfiguration of hibernate, but for postgres I've only change the Driver and the Dialect. Could some give me a help on this? Regards. -- Aurélien DEHAY