* the version of JBossAS you are using
* The version of JDK you are using
* the full stack trace
* a description of what changes you made ( such as apps deployed)
You can supply the first three items by posting the console output, starting from the command line you entered.
Are you using WSRP? If not, please remove portal-wsrp.sar from jboss-portal.sar. It seems that you are running Portal behind a proxy/firewall and that is causing the issue. Please take a look at the wiki: http://www.jboss.org/community/docs/DOC-12633 if you need to use WSRP.