Asp.net page timeouts altough button is clicked in an update panel
<p>I have an asp.net page for a simple blog which looks like</p>

<pre><code>&lt;asp:TextBox ID="txtContent" runat="server" TextMode="MultiLine"&gt;Default Text&lt;/asp:TextBox&gt;
&lt;asp:LinkButton ID="lbSend" runat="server" Text="Send" OnClick="lbSend_Click" /&gt;

&lt;script type="text/javascript"&gt;
    //some javascript to click btnSave in update panel for every five minutes.
&lt;/script&gt;

&lt;asp:UpdatePanel ID="upSave" runat="server" Style="display: none;"&gt;
    &lt;ContentTemplate&gt;
        &lt;asp:Button ID="btnSave" runat="server" Text="Button" OnClick="btnSave_Click" /&gt;
    &lt;/ContentTemplate&gt;
    &lt;Triggers&gt;
        &lt;asp:AsyncPostBackTrigger ControlID="btnSave" EventName="Click" /&gt;
    &lt;/Triggers&gt;
&lt;/asp:UpdatePanel&gt;
</code></pre>

<p>And in the code behind</p>

<pre><code>protected void lbSend_Click(object sender, EventArgs e)
{
    //Gets UserID from session and saves it to table A with txtContent
}
protected void btnSave_Click(object sender, EventArgs e)
{
    //Gets UserID from session and saves it to table B with txtContent
}
</code></pre>

<p>Everything works okay. I fill the form and insert the content into tables with lbSend or btnSave. JavaScript is also clicking btnSave. However when it takes long to fill txtContent, about 40 minutes or more, the page is like expired. Clicking lbSend refreshes the page in an asynchronous way and everything you have written is gone. It is like the page have sleeped and wakes ups when I click. And lbSend works normal when you click it again.</p>

<p>What is the reason of this "sleep" altough btnSave continues to communicate with server? And how can I prevent it.</p>
