HTTP Error 403.14 - Forbidden Error when accessing website

It sounds like your IIS is not processing the routing rules for your application and is trying to find a default.aspx, index.htm, etc. Since it cannot, it is wanting to display the directory listings (which is why you were getting the 404.14).

I just checked my dev setup and I think that your AppPool has to be set on Integrated as opposed to Classic on the Managed Pipeline for the AppPool. I have ran into this before, there may be ways to use the Classic Pipeline, but this would/should be the quickest way to resolve your issue. To check/change the pipeline mode, click on Application Pools from the menu on the left side of IIS, find your AppPool and look in the managed pipeline column. If it is set to Classic -> Right click the AppPool, choose basic settings, then change the dropdown from Classic to Integrated.

If I am incorrect, someone please feel free to correct me on this in the comments.

Edit - Just to add, you can run an MVC app in the Classic Pipeline mode, but you have to do the IIS 6 tricks to get it to work properly. Mainly, you need to turn on wildcard script mapping for MVC to work in Classic mode, If not it expects an .aspx file (or similar) to exist for it to handle the execution pipeline over to .NET from IIS.

Causes this error is removed Global.asax file from your root directory of your site.

To solve this problem add a Global.asax file to your project.

See here: How to add Global.asax file to ASP.NET MVC4 project

In IIS, you need to find out which app pool your application is running from. Just right click the web application under Sites>Manage Web Site>Advanced Settings. The first property should be the app pool.

Now, click Application Pools. You should see a column called "Identity". Add that user to the ACL of the C:\svn\K2\trunk\appteam\web\Chatham.Web.UI.Extranet\ directory. If it just says 'ApplicationPoolIdentity', it can be a little tricky figuring out the user. If it's just running under DefaultAppPool, you can use IIS AppPool\DefaultAppPool.