I repeatedly have to re-sign on after just a few minutes even when I leave my browser up. It's very annoying. None of the other dozen or so forums I've been a part of have done this. I've searched through the settings, but couldn't find anything.
I was having similar issues with my Macbook. The site was signing me out every few minutes and I was losing information that I had typed, as the site would crash when asking me to log in then redirect back to post.
By your use of the past tense, can I assume that this is now fixed for you?