StackOverFlow with FDS

I have an application using Flex Data Services running from Tomcat. I've created Java domain objects as well as corresponding ActionScript objects and everything seems to work fine when I pull the Java objects to the client using Data Management Services combined with the Java Adapter and my custom FlexFactory and a Spring backend. The objects being used have several associations: (ie. Student object references multiple Course objects which each reference a Teacher object, etc). With less than 500 rows in each table (Users, Teachers, Students, Courses, Subjects, etc) things work fine.

However, when I put a significant number of rows of data into some of the tables all of a sudden I get an exception on the server. For example, if I have 100 Teacher rows in my database and those reference 500 Courses and those reference 1000 Students, things are fine. But if I put in another 5000 Students, which are also referenced by these Courses, I get this:

Throwable in RtmpReader thread: java.lang.StackOverflowError
java.lang.StackOverflowError
at java.util.HashMap$KeySet.iterator(HashMap.java:867)
at java.util.HashSet.iterator(HashSet.java:154)
at java.util.AbstractCollection.toArray(AbstractCollection.java:173)
at org.hibernate.collection.PersistentSet.toArray(PersistentSet.java:155)
at java.util.ArrayList.<init>(ArrayList.java:136)
at flex.messaging.io.ArrayCollection.<init>(ArrayCollection.java:44)
at flex.messaging.io.amf.Amf3Output.writeArrayCollection(Amf3Output.java:407)
at flex.messaging.io.amf.Amf3Output.writeObject(Amf3Output.java:147)
at flex.messaging.io.amf.Amf3Output.writeObjectProperty(Amf3Output.java:215)
at flex.messaging.io.amf.Amf3Output.writePropertyProxy(Amf3Output.java:495)
at flex.messaging.io.amf.Amf3Output.writeCustomObject(Amf3Output.java:467)
at flex.messaging.io.amf.Amf3Output.writeObject(Amf3Output.java:165)
at flex.messaging.io.amf.Amf3Output.writeObjectArray(Amf3Output.java:730)
at flex.messaging.io.amf.Amf3Output.writeAMFArray(Amf3Output.java:386)
at flex.messaging.io.amf.Amf3Output.writeObject(Amf3Output.java:151)
at flex.messaging.io.ArrayCollection.writeExternal(ArrayCollection.java:97)
at flex.messaging.io.amf.Amf3Output.writePropertyProxy(Amf3Output.java:485)
...........(continues this loop for several more lines).............

One the front end, the client appears to either hang or timeout with this:

[RPC Fault faultString="Channel disconnected" faultCode="Client.Error.DeliveryInDoubt" faultDetail="Channel disconnected before an acknolwedgement was received"]
at mx.data::ConcreteDataService/http://www.adobe.com/2006/flex/mx/internal::dispatchFaultEvent()
at ::DataListRequestResponder/fault()
at mx.rpc::AsyncRequest/fault()
at ::NetConnectionMessageResponder/NetConnectionChannel.as$37:NetConnectionMessageResponder: :channelDisconnectHandler()
at flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.messaging::Channel/mx.messaging:Channel::disconnectSuccess()
at mx.messaging.channels::RTMPChannel/mx.messaging.channels:RTMPChannel::statusHandler()

I'm not sure what the cause is, but I think it may be related to one of these things:

Possible Cause 1:
The additional rows of data that I'm using to fill my database have some sort of flaw that is creating a circular reference among the objects being used by FDS.

Possible Cause 2:
I do not have the settings correct in FDS concerning lazy-initialization, caching, or some other property that would prevent the data management service from getting stuck in a loop, or trying to basically create one object in the object graph for each row in the database. Obviously if I have 20,000 rows in a table, I do not want the FDS to create 20,000 in-memory objects in the object graph that it uses to supply data to the clients, right?

Possible Cause 3:
I have not setup the fill or sync or whatever methods in my Assemblers correctly that are used by the clients to get data.

Any ideas on where this error might be coming from?