Browser cache perhaps. If the cookies are site wide there should be no problems. IIP uses .threads to verify a user's login status so it's not IIP that's seeing the user isn't logged in. I get that here sometimes when I load the index into my browser. If I use the full url including the index.php?Cat= then the correct view is loaded. If I just visit
www.threadsdev.com then my browser's cache seems to take presidence. Perhaps one way around this would be to have the index page check the URL and see if it includes "index.php?Cat=" and if not reload the page to include that so it's a up to date view?