Directory Listing Denied:The Virtual Directory does not allow Contents to be listed

The Project in which i am working consist of three phase testing as Test-QA and then production. Once we are able to deployed successfully then we implement that change in production which is ideal for everyone.As we need to implement Ajax in the sharepoint farm, it requires .net 3.5 with sp1 to be deployed first. After deploying .net 3.5 in the SharePoint test enviornment, we faced some issues and due to some reasons, we had to revert back the changes and uninstalled .net 3.5.

Now the problem starts, after the uninstallation, when we tried to browse the site, we faced wierd error message "The Virtual Directory does not allow Contents to be listed".

After doing some troubleshooting, we were able to resolved the Problem. The steps that we followed as follows:-
Resolution Steps:-
-IIS Manager
-Site
-Properties
-Home Directory tab
-Configuration
-Wildcard Application Maps
-Add the location path of the aspnet_isapi.dll
C:\windows\microsoft.net\framework\v2.0.50727\aspnet_isaspi.dll

Note:-Ensure that the checkbox Verify that the file exists is unchecked, otherwise error 404 page not found will be displayed.
This is because the data is rendered from the SQL database and not from IIS locally, and sharepoint will process this on the run while the site is being accessed.