Hello Obalesu N,

This dll file is not part of the Infragistics packages. However, I noticed that the same question has been discussed in the following thread that you might find helpful:

Hello Obalesu N,

Thank you for your response.

By default this control does not work with these standart SharePoint components because of teh differences in the postback mechanisum that are used by SharePoint and ASP.NET. The ASP.NET AJAX UpdatePanel control must change the page’s postback behavior to enable support for asynchronous postbacks and partial rendering. However, in a SharePoint application, these modifications cause a JavaScript error. This is because SharePoint attempts to make a similar change. TheSafeScriptManager control corrects the JavaScript problem.

What I can suggest for resolivng you issue is adding a ererence to Microsoft.Practices.SPG.AJAXSupport.dll. Add a SafeScriptManager control to your page and set the EnableUpdatePanelSupport flag to true. This changes the postback script that is needed for the UpdatePanel control to work in a SharePoint environment. For example:

[code]

<%@ Register

   Assembly="Microsoft.Practices.SPG.AJAXSupport, Version=1.0.0.0, Culture=neutral, PublicKeyToken=8768CCAE1C3C9EB2"

   TagPrefix="spg"

   Namespace="Microsoft.Practices.SPG.AJAXSupport.Controls" %>

<spg:SafeScriptManager ID="SafeScriptManager"

                                                   runat="server"

          EnableUpdatePanelSupport = “True”

                                                   />

<asp:UpdatePanel runat=”Server” id=”MyUpdatePanel”>

 ...

</asp:UpdatePanel>

[code]

Some further reference could be found at: