It does look like a datasource problem, that's for sure.
Perhaps you have a way of testing your datasource apart from Hibernate? Like just write some code that looks it up, opens a db connection, queries the database, and closes the connection? If there's an easy way to do that, it might be worth your time.
Your hibernate.cfg.xml file might have a peculiar setting as well. Post it and maybe there's something in there that stands out.
Database, app server and how the datasource is being managed or created might be great info as well.
I believe that you don't need these lines in your persistence.xml file:
They are already in your tomcat config (context.xml) When you call em.getTransaction(); you're asking the container for a new connection. But if you keep these properties in your persistence.xml, then you're saying that hibernate will handle you connections, not the container [ June 10, 2008: Message edited by: Rodrigo Lopes ]
Hmm, thanks, but the same exception is thrown without these properties in persistence.xml. It is thrown even if there is no properties. Has anyone other idea's? [ June 17, 2008: Message edited by: Max Vaha ]