Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 8000401a

If you add a reference to Microsoft Excel and then try to use it within your ASP.NET application you may receive the following errors.

Server Error in '/excel' Application. 

Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 8000401a.

We referred this link for the DCOMCNFG settings required on Windows 2003 server http://blog.crowe.co.nz/archive/2006/03/02/589.aspx   . Even after the settings the problem was  not resolved and following error started to appear

Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 80070005.

Make some changes also in ASP.Net Site’s web.config file.

Given below is the settings for web.config file.

<identity impersonate="true" userName="DomainName\administrator" password="password"/>

            <authentication mode="Windows">           </authentication>