Authentication & authorization issue for IIS

Hi

I am using COM object in Web Application. There is a problem to solve authentication & authorization issue for Server site. At the time of using the COM object it shows the error " ACCESS DENIED ". If I am writing <identity impersonate="true"> in web.config, it is OK but the AJAX file is not accessible for that reason.
if I am using iisreset in Run command, then the whole application is OK, but it is not possible to reset iis again and again in production server. Have you any idea for this?

For more clarification, suppose there is a link in a Web page interface. After click the link, one Word document will open. How we solve authentication/authorization issue in iis without affecting to other files like AJAX.

I am using ASP.NET with C#. I am not using MTS.

any idea, please write.

regards