The auto logoff is the time that a user must remain inactive before their login session expires.
It had been set to 15 minutes ~ and is now increased to 30 minutes.
This setting also controls how long a user will remain shown on Who's Online after their last activity.
Please note that by selecting the "Remember Me" option beside the log in, registered users (with cookies active for this site) can elect to conveniently auto relog in (using their registered user username/profile) at anytime they return to the site. Note that this won't stop users being logged out if their inactivity exceeeds 30 minutes, however it will seamlessly relog you in once you return.
For those with concerns about cookies on general websites etc, a simple solution is to use browser options to permit (only) websites you nominate to run cookies.
In IE6/7 the settings are found under Tools>InternetOptions> Privacy>Sites.
Simply adding www.star-board.com
Cheers ~ Ian