This is just me thinking out loud:
If you're not using any cookie cleaning software or declining cookies, then it might be a problem with adblocker. I cannot say this for sure though but I faced the same thing on my laptop (albeit only twice) which uses an adblocker plugin, and I haven't seen a this problem on my Mac. In fact, I've been logged in continuously since the first time. Furthermore, when we go ahead and change things on the site, then it makes the current cookies invalid - which can be the cause of at least a few of the times.
Can you describe your exact actions when refreshing the site multiple times or up to you getting logged out? Like, do you spam the F5 button; regularly refresh to check balance; refresh, complete captcha, refresh, surf around, refresh, rinse & repeat; or which approach are you using? Might help us narrow down the problem.
Thanks!
most of the time i get logged out when the mining timer hit 0:00, (after about 45 minutes) when the page reloads i have to log in again. mybitmine is exempt from the add blocker as your site does not work when adblocker is switched on.
i can go to other pages just before the reload of the mining page hits 0:00 and all works fine but when i go to the mining page i have to log in. it does not happen all the time.
when i clean cookies i expect to log in again to your site, and many others, but cookies only get cleaned when i clean them, they are not cleaned automatically.
it does not depend on me staying active ( see above about surfing your site then loading mining page) ever 5 minutes or waiting for the timer to run to 0:00.
it does not depend on if i close the page and reopen it later. i have even rebooted my computer loaded your site and i can still be logged in.
its nothing serious just a little annoying some times when i can navigate the site but must login again 5 seconds after i have viewed another page on mybitcoin.
its just one extra click and 1 extra page to load, but thought you might like to know.