Reviewing you error:
System.Exception: Unhandled Error: ---> System.Web.HttpException: Server cannot modify cookies after HTTP headers have been sent. at System.Web.HttpCookieCollection.Add(HttpCookie cookie) at Microsoft.ScalableHosting.Security.RoleManagerModule.OnLeave(Object source, EventArgs eventArgs) at System.Web.SyncEventExecutionStep.System.Web.HttpApplication+IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) --- End of inner exception stack trace ---
There is something trying to modify your cookies on this request. If you take a look at the code for DSfckStyles.aspx, you will see that it is so simple and there is no access to any cookie.
You error says at System.Web.SyncEventExecutionStep.System.Web.HttpApplication
There are some problems with response.end and response.clear with some modules. Those problems can be resolved, but we must identify the httpmodule first.
Have you tried to run DSfckStyles.aspx directly? if not, maybe it could give you more information.