I dunno who else remembers this bug, but I've been getting logged out automagically at quite short intervals (happened at least twice this morning so far) again.
Session on this forum is binded to your IP address. Once it's changes you need to login again. Same valid for in-game authentification.
I ran some tests, and the only thing that uniquely identifies an user which is sent by the browser, is your IP, MAC address would solve all problems, but be happy it doesn't (tracking cookies and other privacy stuff). I can probably rework the system and allow you to auto-login from any IP you have logged in from manually before, but I can't promise anything, and that still won't fix it for people who constantly change IP. Disabling the whole security feature is not something I'm keen off, because anyone with your cookie can auto log himself in.
Really, having stale cookies sometimes does this. Clear your current cookies for Uberent.com. When you get back on the site for the first time afterwards, will collect all fresh cookie data. Likely, a conflicting old one will stop logging you out. Or not, but its worth a try.