I think I know what the problem is. There was a thread here which discussed something similar. Basically, the @Schedule by default creates a persistent timer. The @Schedule is expected to create an auto-timer on deployment of the bean. But ideally, it should not create the auto timer for an already persisted timer (or it should clear off the previous instance). I think there was a JIRA for this one, which I probably missed for 6.0 Final. Let me find that thread first.
For now, delete the JBOSS_HOME/server/<servername>/data folder and as a workaround, use:
@Schedule(minute="*/5", persistent="false")
That should get you past these issues.