I had the instant messaging package Trillian installed prior to installing JBoss. Here, Trillian is listening to AOL on port 1098, which is the same port JBoss wants to use. Rather than look to reconfigure JBoss, I stopped using Trillian until I can find out how to get Trillian to look at another port. Once Trillian was stopped, JBoss started up correctly.
If you need to chat and work at the same time, you can change the value of the RMI Port in your
$JBOSS_HOME/server/[your config]/conf/jboss-service.xml
<attribute name="RmiPort">1098</attribute>