You should not be accessing files during the Application_Start event which appears to be what is happenig with this ClientDependency access denied error. In cases where identity impersonation is used this will cause problems.

It also caused problems back in 2006 when you did the same with EventQueue:

http://www.dotnetnuke.com/Resources/F... 

From http://www.odetocode.com/blogs/scott/archive/2006/07/12/impersonation-and-application_start-in-asp-net.aspx:

Impersonation and Application_Start in ASP.NET

Q: I want to query my database and cache some static data during the Application_Start event. SQL Server requires a trusted connection, and I'm using impersonation in web.config.

<identity impersonate="true" userName="jacque" password="crackme"/>

This works everywhere except Application_Start. The code in that method can't connect to the database. What's the dilly?

A: The short answer is that impersonation isn't "on" during Application_Start, so SQL Server is seeing the worker process identity (NETWORK SERVICE or ASPNET) instead of Jacque's identity.

Application_Start is an odd event. It's not really a request related event, but of course it won't fire until the first event arrives. The ASP.NET runtime doesn't start impersonation until it begins to process the request in earnest. This event fires just before impersonation begins, during a time when ASP.NET is laying out the cocktail napkins and setting up for the party.

There are at least a couple workarounds for the problem. You could use a Singleton* design pattern, and initialize the Singleton during a request when impersonation is active (perhaps during the BeginRequest event). You could also run the worker process under an identity with rights in SQL Server.