I found the problem. I needed to be logged in as root.
Actually, it is recommended that you not run JBoss AS as root. I either run it using my account, or as a separate 'jboss' account. When doing this, you have to make sure that the account used to run JBoss AS is the owner of the entire JBoss AS directory structure.
Granted, but I'm happy to have a solution even if it's a bad one.