Re: logged in time period.
It is already set to 15 minutes (up from the 10 minutes it was in the past).
Its possible to increase this further but its playing off security (ie where people don't specifically log off on a shared computer) against problems like yours and I'd be reluctant to increase this further as it exposes users to a greater degree of potential hacking.
If you are not using a shared computer, ticking the "remember me" box when you logon should avoid this issue as it will automatically log you on for the post. Just remember to "logoff" if you don't want that pc to autol-logon next time.
A piece of advice, if you make a long post, select the message text and copy it (CTRL-C) before you post. That way if it all goes pear shaped you can create a new post and paste it back in (CTRL-V) in a matter of seconds.
Your original post will be completely lost, as far as the server was concerned it was an attempt by a "guest" to post the message and we only allow logged on users to post.