Using the mobile site on iPhone 4S, running on iOS8 and using Safari.
If I follow a link from a thread, which opens up a new Safari page, read and then close it, the MN page I was on reloads and logs me out in the process. The same happens if I go to a different app but keep MN open. I can be mid-reply to a thread, go on something else to check something for literally 2 seconds, but as soon as I flick back to MN, it reloads and logs me out. So I have to log back in and type my reply all over again. This only happens on MN and no other sites I use.