JBoss tries to use port 1098. But there is nothing preventing another application from using it if it finds it first. I actually had a bit torrent using the port. I disabled the torrent and jboss started fine.

I discovered the application that was using the port by typing netstat -b from the command line in Windows XP. I understand this command only works in XP. Look around to find something similar if you're not on XP.

One condition that causes this error is if JBoss was shut down improperly (or if it's still running). In that case, you might just want to reboot.

There is a way to reserve port numbers so that other applications don't use them. Also, it is possible to change the port number that JBoss uses. You can read the directions to do either of these here.