IE duplicate cookie problem
During testing of one of our applications, we found a problem with login to the site. Spent 3 hours debugging it, and finally concluded that server side software works correctly, but IE7 (7.0.5730.13) does not. IE7 sends two different cookies with same name. /Usually this is the last thing which can come to your mind when you debugging your Web software./
As result, our server software reads first (invalid old) cookie, and the whole authentification provess is broken.
We were unable to find exact conditions to reproduce it: it just happens sometimes… The only way to fix it, is to restart IE completely (close all windows and start again). I will post updates if I find more information on this topic.
Update: One more reference about the same problem. So we know how to fix it, and going to do it now.
Final words: usually you investigate your own code to find the problem. Finding big problems like this in well known browser, is not really expected.