Something weird just happened to me. I was navigating the forum without having logged in and I clicked to see the last message of a post. Then I looked at the address line and, to my surprise, the first parameter in the GET line was PHPSESSID, which was assigned a hex chain maybe some 32 characters long. It really called my attention that PHP would send this sensitive information via GET, which anybody could copy and use to impersonate somebody else and I was surprised also that I hadn't seen this before. So I moved to another topic and the parameter wasn't there anymore. I returned to the same topic and no, it didn't do it, so I don't know how to reproduce it. Why could this be?