I know it's been awhile since this topic was active but my users are having this issue. The issue of being constantly logged out, not matter what the browser, while using the boards (www.lcficmbs.com). I have tried *everything* suggested in this thread yet the problem still persist.

HTTP Referer Check is disabled
Cookie Path is set to default.

I tried Custom Cookie Prefix but when I set one suddenly I had users who complained that they couldn't log in at all - they are claiming that they did clear their cookies.

This is what I am running:

UBB 7.5.8
Apache 2.2.31
PHP 5.4.43
MySQL 5.5.42

I've actually tried using PHP 5.6 (my host is currently running it as a beta) and still no dice.

I've email UBB support with no response yet. (I can't even get to the 7.5.9 software to try upgrading, which I addressed in my email.)

I've had a very small amount of users complaining about this since we upgraded in 2014 but suddenly it's become a big issue in the last few days. Our host was rebooted 2 days ago due to a SMTP issue but I highly doubt that could cause the login issue to get worse. The server has been rebooted several times over the years.

Any suggestions would be appreciated as it's becoming a very sore subject between me and my users. No matter what I try it does not work.