I have been working on a few custom Web Controls/Web Parts. One of the controls is a stock quote which updates every 10 minutes (or whatever the user defines). This is done by using an UpdatePanel and Timer. In my custom application.master page, I have the stock quote Web Control. When I attempt to view the People and Groups page in Site Settings (/_layouts/people.aspx?MembershipGroupId=4), I receive the following error.  

Script controls may not be registered before PreRender.   at System.Web.UI.ScriptControlManager.RegisterScriptControl[TScriptControl](TScriptControl scriptControl)
   at System.Web.UI.UpdateProgress.OnPreRender(EventArgs e)
   at System.Web.UI.Control.PreRenderRecursiveInternal()
   at System.Web.UI.Control.PreRenderRecursiveInternal()
   at System.Web.UI.Control.PreRenderRecursiveInternal()
   at System.Web.UI.Control.PreRenderRecursiveInternal()
   at System.Web.UI.Control.PreRenderRecursiveInternal()
   at System.Web.UI.Control.PreRenderRecursiveInternal()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

What’s weird is I can access other pages within _layouts without issues. My thinking is there must be some extra things going on in the people.aspx page which is causing the error. I will review it over the weekend. Anybody else seen this?