Glassfish 3.1 Problems - "Attempting to execute an operation on a closed EntityManagerFactory"

Recently I tried to re-deploy a EJB jar application into the GlassFish 3.1 Server but got the following error:

java.lang.IllegalStateException: Attempting to execute an operation on a closed EntityManagerFactory.

To fix this problem do a clean deploy by first undeploying the application and redeploying the application.