I just moved my forum to WWF, seems that the "Active Users" link in the default.asp always report a wrong message to me.
most of the time when I visit the homepage of the forum first, It report that there's "nn" user active, but when I open the "Active Users" page to look who is online, the number of the user in this page always less than the first page. when I back to first page, I see a same number as the "Active Users" page.
Does the user alwayls leave during the several seconds when I chang the pages?

and an other question, how can I chang the time period that the system to estimate a no active online user is offline?

The active users are derived from the global.asa page in the root directory of your website.  It displays a hit for every new user that enters the site, BUT, usually it has a default timeout of 20 minutes - which means that if someone enters the site, it counts them as an active user.  If they leave right away, it won't show a decrement until 20 minutes after they enter the site.