I encoutered a problem when i called the .aspx page using the Ajax calls of  "XMLHttpRequest"  Msxml2.XMLHTTP.5.0. I am currently working with VS.NET 2008 (.net framework 3.5). Below are the list of errors i saw when i was going through the Application event log of my system.

scriptle2.dll, version 9.0.21022.8,

Faulting application devenv.exe, version 9.0.21022.8, stamp 47317b3d,
faulting module scriptle2.dll, version 9.0.21022.8, stamp 47317e18, debug? 0, fault address 0x0000328c.

.NET Runtime version 2.0.50727.3603 - Fatal Execution Engine Error (7A2E10D2) (0)

Hanging application iexplore.exe, version 7.0.6000.16915, hang module hungapp, version 0.0.0.0, hang address 0x00000000.

I solved the issue, by doing the following things.

(1) I installed the "AjaxControlToolkitBinary" and "MicrosoftAjaxLibrary" zip files from the below link and unzipped them to the downloaded folder.

      http://www.asp.net/ajax/downloads/

      and classic ajax calls starts working. If remove any one of the above two then i am getting the above errors.

(2) I also installed .net framework 3.5 SP1 and this sp1 is not needed for the ajax calls to work (First i installed SP1. Ajax calls did not work, then i installed the above libraries from the above link then the ajax calls start working).

I would what exactly what needs to be done?

When i tested in vs.net 2008 it is working good, but when i move this to other regions like QA an UAT i need to know exactly what i have to do?

As i mentioned just downloading and unzipping did the trick for us.

 Note:-  Before doing all the above i did the below two things too

(1) Added the "AjaxControlToolkit.dll" in the bin directory of my web site

(2) In "Web.config" the below entry been added

 <add namespace="AjaxControlToolkit" assembly="AjaxControlToolkit" tagPrefix="ajaxToolkit"/>

 Thank You