I just wrote a blog post on my team blog on using FREB to troubleshoot a simple error message. I’ve taken an example of a HttpModule setting the Response status to 400. This is not a common scenario, but I just want people to use FREB extensively in their troubleshooting an error message – to see which module set the status, and take it from there.
Read the post here - http://blogs.msdn.com/webtopics/archive/2009/06/12/troubleshooting-a-simple-error-message-using-freb.aspx
And, please do subscribe to my team blog RSS feed where we have bunch of folks blogging on issues which are most common to our customers, best practices, known issues, and workarounds, etc. That’s our official team blog of Microsoft IIS and ASP.NET support team.
Hope this helps!