I would like to store my session state out of process from IIS, so my session state does not disappear everytime the ASP.NET Worker Process recycles.

However, it seems you are storing non-serializable objects in session state making it impossible to do so.  It also seems like a bad idea to use session state to st

See:
http://msdn.microsoft.com/en-us/library/87069683(VS.71).aspx

<system.web>
<sessionState mode="StateServer" stateConnectionString="tcpip=dataserver:42424" cookieless="false" timeout="20"/> </sessionState>
</system.web>

When I do this I get this error:

Unexpected website error: Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode.

System.Web.HttpException: Unable to serialize the session state. In 'StateServer' and 'SQLServer' mode, ASP.NET will serialize the session state objects, and as a result non-serializable objects or MarshalByRef objects are not permitted. The same restriction applies if similar serialization is done by the custom session state store in 'Custom' mode. ---> System.Runtime.Serialization.SerializationException: Type 'Asi.iBO.ContentManagement.CWebUser' in Assembly 'Asi.iBO, Version=15.0.3.2401, Culture=neutral, PublicKeyToken=null' is not marked as serializable.
at System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type)
at System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context)
at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo()
at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter)
at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.Serialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter)
at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck)
at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck)
at System.Web.Util.AltSerialization.WriteValueToStream(Object value, BinaryWriter writer)
--- End of inner exception stack trace ---
at System.Web.Util.AltSerialization.WriteValueToStream(Object value, BinaryWriter writer)
at System.Web.SessionState.SessionStateItemCollection.WriteValueToStreamWithAssert(Object value, BinaryWriter writer)
at System.Web.SessionState.SessionStateItemCollection.Serialize(BinaryWriter writer)
at System.Web.SessionState.SessionStateUtility.Serialize(SessionStateStoreData item, Stream stream)
at System.Web.SessionState.SessionStateUtility.SerializeStoreData(SessionStateStoreData item, Int32 initialStreamSize, Byte[]& buf, Int32& length)
at System.Web.SessionState.OutOfProcSessionStateStore.SetAndReleaseItemExclusive(HttpContext context, String id, SessionStateStoreData item, Object lockId, Boolean newItem)
at System.Web.SessionState.SessionStateModule.OnReleaseState(Object source, EventArgs eventArgs)
at System.Web.SessionState.SessionStateModule.OnEndRequest(Object source, EventArgs eventArgs)
at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)