asp.net web application goes to login page after about 15 minutes
<p>I have a web application, and for some reason which I cannot figure out, It goes to the login page every 15 minutes (I believe the session is idle). I have no where web config file that specify a timeout even close to that. Has anyone ever had an issue like this or know where I could look to try and fix the problem? thanks for any help.</p>

<pre><code>&lt;authentication mode="Forms"&gt;
  &lt;forms loginUrl="~/Account/Login.aspx" 
         timeout="90" 
         defaultUrl="~/" 
         name="" 
         protection="All" /&gt;
&lt;/authentication&gt;
</code></pre>
