Why does the Combo.SelectedValue get lost after some time
<p>So I have this asp:DropDownList on a page. It renders like this (in IE7):</p>

<pre><code>&lt;select name="ctl00$cphFilter$cbLista" onchange="javascript:setTimeout('__doPostBack(\'ctl00$cphFilter$cbLista\',\'\')', 0)" id="ctl00_cphFilter_cbLista" class="agsSelect"&gt;
  &lt;option selected="selected" value="4350"&gt;A&lt;/option&gt;
  &lt;option value="4352"&gt;B&lt;/option&gt;
  &lt;option value="4349"&gt;C&lt;/option&gt;
  &lt;option value="4348"&gt;D&lt;/option&gt;
</code></pre>

<p>And then I have a grid and a button on the same page. When the user clicks the button the selected item of the dropdown is read (well a datasource object reads it) and the grid does a databind after a trip to a DB where it gets some data based on that selected value.</p>

<p>This works fine most of the time. However sometimes, the selection in the dropdownlist seems to get lost even though the rendered page says the A is the selected item. </p>

<p>The datasource object is defined like this: </p>

<pre><code>&lt;asp:ObjectDataSource ID="dsVM" runat="server" EnablePaging="False" SelectMethod="Select" SortParameterName="sort" TypeName="X.Business.Entities.LPVM.BE"&gt;
 &lt;SelectParameters&gt;
  &lt;asp:ControlParameter Name="listaId" Type="Int32" ControlID="cphFilter$cbLista" PropertyName="SelectedValue" /&gt;
 &lt;/SelectParameters&gt;
&lt;/asp:ObjectDataSource&gt;
</code></pre>

<p>Any ideas why the grid would reload its data with a select parameter that is 0 instead of the selected value of the dropdownlist? </p>

<p><strong>EDIT</strong>
Suppose the dropdownlist is bound, the user selected B and the grid is bound as well and shows the right data. Now, I wait 2 minutes and I click the Refresh button. Surprisingly, at this particular moment the dropdownlist.SelectedValue (which I already know it was 4352 before I clicked because that's how it looks in the rendered page) is actually an empty string. Where did the value go?</p>
