Page does not load when ScriptManager is not included on MasterPage, but does when ScriptManager is commented out
<p>I have been editing an existing ASP.NET website, and removing old code that is no longer necessary.  </p>

<p>On the MasterPage there was a ScriptManager control that I removed.  The page would then stop loading any content, and I would just get an empty body tag.  However, if I leave the ScriptManager control in, but surround it with &lt;!-- --&gt; to comment it out, the page then loads.  </p>

<p>If I uncomment the ScriptManager, I get an error in my Firebug console that reads "Sys.ArgumentException: Sys.ArgumentException: An element with id 'form1' could not be found.
Parameter name: elementOrElementId."  The page still loads properly.</p>

<p>I checked to see if there was an UpdatePanel or anything else that I was aware of that might be using the ScriptManager and I can't find anything.</p>

<p>Can anyone tell me why this behavior is occurring?</p>
