Benjamin Gavin published the solution of a timeout problem with a Silverlight 4 RIA Services application which utilizes Windows Authentication.
Source: Virtual Olympus Blog
This will be a pretty short and sweet blog post, but the issue that I describe caused me enough headaches, and was hard enough to ‘Google’ that adding more ways to get there is in and of itself worth it. The problem I ran into was with a Silverlight 4 RIA Services application which utilizes Windows Authentication and needs to run as an out of browser application. The application needed to get detailed user information in order to properly construct the initial application user interface. The problem is that the Authentication Service call was timing out whenever I ran the application, and my RIA Service was never even executed.