-> YES, I am having that problem RIGHT NOW, in fact, I hope to be able to finish this post, since my last two got wiped when I had to re-login. Getting a PAGE EXPIRED notice along with the un-logging of my account every minute or so...
-> I haven't changed anything on my computer configuration, and this as never happened before. My symptoms are EXACTLY as you described, when I went to post a reply or hit HOME or even the other links on FORUM ladder, I am no longer logged in.
-> NOT a cookie thing.