Possibly related:
I specify "No" under "Remember Me" (shared computers, always) -- and I keep getting logged out on virtually every change of screen. Makes it a bit hellish to reply to topics
Edit: Literally after posting this, I was logged out again. Logged back in to make this edit/note, based on past experience might have to save the text and log in
again to actually get it submitted -- and will probably have to log in again after submitting this. So it's a bit extreme.