No, this doesn’t happen for me.
Which web browser are you using? Use either Chrome or Firefox and make sure to instruct the browsers to NOT delete the cookies of plex.tv when they’re closed.
Are you using one of these browser features which do sync the login information and open browser tabs between several computers and mobile devices?
Apart from that, I can only recommend to repeat the procedure in
Use method 2.2: You need to reclaim your server, but don’t dare to touch the Windows Registry
