I have not been able to find anything about this problem, so it must be
configuration on our server, somehow...

What we are observing is on Windows Server 2003/IIS 6 our AJAX UpdatePanels
are not resetting the IIS Session timer. Thus, if the default IIS Session
Timeout of 20 minutes is used, our logged-in users are always receving
Session timeout in 20 minutes, regardless of what UpdatePanel activity is
happening on the .aspx page.

Has anyone seen this problem and does anyone have a solution for me?

Thanks very much, in advance.
--
Mike McAllister

the updatepanel uses XMLHTTPRequest to get the html to display in the
panel. XMLHTTPRequest will send the session cookie, but on response it
does not read and update the browser's session cookie, so after 20 mins
the session cookie times out (in the browser) and is no longer sent to
the server.

you can switch to cookieless sessions or update the browser cookie using
a server request via an img or iframe.

-- bruce (sqlwork.com)