I have a silverlight 5 app that makes some WCF requests. When the silverlight app is hosted locally on an IIS 7.5 server it works fine, but when I run it from a remote IIS6 box there are issues. The app loads fine and presents the login UI. After trying to log in, a couple WCF service calls are made (successfully), but the response causes silverlight to stop responding and the browser eventually asks to kill the non-responsive silverlight app. I am mostly confused because it works fine in IIS 7.5 Note that I am accessing the same WCF services hosted on a remote box in both instances, and both times I am getting successful responses. It is only in IIS6 that the app becomes non-responsive.