I've had this happen to me plenty of times, but I'm thinking it's something my browser does.. At home (like now) I don't usually get timed out, but at work I think I get like four minutes at the most... I (usually remember to) copy the whole post to the clipboard (pc memory) before I post, because sometimes it doesn't stay.. One trick I've learned, is that if you start in "Post Quick Reply" but then instead of posting, if you think you're timed out, click "Go Advanced," USUALLY it lets you log in then takes you to a preview and saves what you've written..