This is only on the additional web server, this problem is not happening from the website on the poller. For those interested, support ticket #90235.
Orion Website Error
An error has occurred with the Orion website.
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ServiceModel.Dispatcher.NetDispatcherFaultException: The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter http://www.solarwinds.com/2007/08/APM:GetApplicationsResult. The InnerException message was 'Deserialized object with reference id '6' not found in stream.'. Please see InnerException for more details. ---> System.Runtime.Serialization.SerializationException: Deserialized object with reference id '6' not found in stream.
Installing the APM 2.5 Additional Component fixes this issue :-P
I was under the impression this was packaged in the 9.1 additional web server install; my mistake.