org.hibernate.AssertionFailure: null id in entry (don't flush the Session after an exception occurs)

I have a hibernate and JSF2 application going to the deployment server and suddenly throwing an org.hibernate.AssertionFailure: null id in exception. I will provide the stack trace and code immediately but here are four important issues first:

1. This happens only on the deployment server (Jboss & MySql running on Windows Sever 2008.) It does not happen on my development machine (Tomcat and MySql running on Windoes 7 Pro) and also not on the staging environment (Jboss and MySql running on Linux.)

2. Researching this, it seems that people get this error when trying to insert an object. But I get the error when I'm doing a simple query. (various different queries, actually, as the error pops up on several pages randomly.)

3. The error hits only every now and then. If I do a Jboss restart it goes away, but a time later returns. Also, it's not consistent, on some clicks it's there, on others it's not. Even when it hits, when I do a simple refresh of the page it returns fine.

4. I'm using c3p0 (config below)

Any idea what's going on?

The code details:

This happens on an address object. Here's the full hbm:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.idex.auctions.model">
<class name="Address" table="address" lazy="true">
  <id name="addressID" column="AddressID">
        <generator class="native"/>            
  </id>

  <property name="street" column="street"/> 
  <property name="city" column="city"/> 
  <property name="zip" column="zip"/> 
  <property name="state" column="state"/> 
  <property name="region" column="region"/> 
  <property name="country" column="country"/> 

  <many-to-one name="user" 
       class="com.idex.a