Sorry, i just recognized that other people already reported this problem in the forum.
It seems to me that there is a version conflict between the 'commons-fileupload.jar' used in CMSPortlet and ForumsPortlet and the one used by the EJB3-Deployer. I solved the problem by deleting the 'commons-fileupload.jar' of the EJB3-Deployer (server/default/deploy/ejb3.deployer/commons-fileupload.jar). Since my EJB3 application works without problems, i guess it wasn't really needed by the EJB3-Deployer.
i simply unzip the bundled version of the portal in winxp and redhat 9 and works fine... i think its a problem in the install configuration.
roy: gracias por postear el wiki sobre la configuracion del repositorio ;)