This isn't helpful but I tried everything, and nothing worked. I then stopped trying and for no reason at all it remedied itself. We've had a few of these posts over the last year or so, and it always appears to remedy itself for the affected user. I don't doubt it will for you too, you'll just have to ride it out until it does. I find it particularly frustrating as ironing out these glitches in our software is part of my job, but I could find no rhyme or reason for this problem despite spending quite a while on it.
I suspect this is the reason. You need to add it to trusted sites or whatever the config on your browser needs then it seems to stop.
You have to go to the secure site be and to stay logged in https://barnsleyfc.org.uk/forums/bulletin-board.130/ i have the problem if i go to http://barnsleyfc.org.uk/forums/bulletin-board.130/ would it be possible to pop a redirect on to https?
Ok have put a redirect in place to the https version of the site which I think could fix the issues. @YTBFC @BfcTim @Sheriff let me know if the issue has gone away please.
Early indications are positive. I was still having a problem with it earlier today, but it seems to be keeping me logged in when I re-visit now.