Dynamics 2011 ASPX Pages in IFRAME

I am in the process of upgrading a Dynamics 4.0 ISV solution to Dynamics 2011. The Dynamics 4.0 solution hosted content in the ISV directory within an IFRAME in Dynamics.

Since configuring this same behavior in Dynamics 2011, I now get the age old error:

System.Web.HttpException Error message: The state information is invalid for this page and might be corrupted.

On any second request 开发者_开发技巧submitted by the page in the IFRAME. That is, if I click Submit once, it works. The second time I click Submit it busts and throws the above error.

Any ideas on the cause or on how to resolve this?

Thanks.

UPDATE: Even with the page directive EnableViewState="false", I still get this error on second post.

UPDATE 2: I've narrowed it down and I can see that it's an UpdatePanel that's triggering it. Once the first request is made using the UpdatePanel, the subsequent ones fail with the aforementioned. error....

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The ISV directory has been deprecated in CRM 2011. There are a couple options when moving forward.

1. Convert the aspx assets over to web resources (html/javascript/silverlight).
2. Host a website independant of the CRM deployment and use Federated Services to authenticate inbetween.

Information is currently sparse on the second option. Here are a couple links which may help:

Implement Single Sign-on from an ASPX Web Page or IFRAME

Microsoft Dynamics CRM 2011 Claims Based Implementation Guide

Sorry for being so vague, but there is no silver bullet in this case.