asp.net failed to run in dot net 4.0
<p>The website was developed in dot net 3.5 SP1 and running ok within dot net 3.5 SP1.
But, after recompiled it into dot net 4.0 and changed the app pool to "integrated", it failed to run. The symptom is that the website was running ok for few minutes. Then, the following message will appear:</p>

<blockquote>
  <p>[NullReferenceException: Object
  reference not set to an instance of an
  object.]<br>
  System.Web.PipelineStepManager.ResumeSteps(Exception
  error) +197<br>
  System.Web.HttpApplication.BeginProcessRequestNotification(HttpContext
  context, AsyncCallback cb) +89<br>
  System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest
  wr, HttpContext context) +189</p>
</blockquote>

<p>If we recycle the app pool, it will work for a few minutes and then same error appear.</p>

<p>Any help is appreciated.</p>

<p>Lau.</p>
