Thanks, but the instructions are for EJB 2.x timers. I configured the EJB 2 timer to not use any persistence, but I still got the same error. It looks like with JBoss 6.1.0 that the EJB 3 Timers are deployed in common/deploy/jboss-ejb3-timerservice-mk2.jar. I didn't see a way to configure the EJB 3 timer to disable persistence.
I found the source code for jboss-ejb3-timerservice-mk2 at https://github.com/jbossejb3/jboss-ejb3-timerservice.git and commented out the construction of the hibernate query. That worked, but I'm looking for another solution where I can disable the EJB 3 timer.