and a few hours later, i can confirm that i'm logged out :S Sounds odd, this one. Remember that Drupal does not use any cookies of its own and just repies on the inbuilt PHP session handling cookie. It seems that drupal and the browser are both behaving correctly. Is something happening in your Apache/PHP to cause it to lose PHP sessions? Server re-configs / reloads / restarts? Cleaning of temp data?
I don't know, the site is hosted at canaca.com and I obviously have just a limited access. I can just say that this behaviour isn't something recent but it has been a constant.
Also, I had another forum engine on the same site and the cookies always worked perfect. I was always logged in on that one.
Here you can read about the rest: http://www.cesspit.net/misc/phpinfo.php
-HRose / Abalieno