the issue here was the same as one i previously came accross.
when running the web app in debug mode it automatically uses http:\\localhost

when open new windows/popups from inside a previously existing window, these popups can use the sessions, however localhost does not recognise them.

so when i hit F5 or play i need to change the http:\\localhost to http:\\127.0.0.1 or whatever your ip address is and it will work

begs me to ask a question,

how can you set IIS to use http:\\127.0.0.1 when running the application and not use http:\\localhost???