I am trying to set up Single sign on for 2 websites that reside on the same domain
e.g.
http://mydomain (top level site that contains a forms-auth login page
I had used on the httpModules section, as there were items in the parent that did not exist in the bin dir for the child (/admin)
In doing so (using that is ) I had inadvertently cleared the FormsAuthentication module specified in the web.config in
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG
so i needed to re-add those explicitly to the child (/admin) config