Rare Http Errors

As software developers you may encounter following errors. I my self encountered them and had to research a bit to find the reasons and solutions. Following are the errors and corresponding solutions

HTTP Error 500.21 - Internal Server Error
Handler "PageHandlerFactory-Integrated" has a bad module "ManagedPipelineHandler" in its module list

The solution for this problem is available in the following web URLs
http://forums.asp.net/t/1480233.aspx
http://forums.iis.net/p/1149449/1869918.aspx
I was facing this problem because ASP.NET was not registered properly. This often happens when you remove and add the IIS component again or you installed IIS after .NET. Executing the following helped me.
%windir%\Microsoft.NET\Framework\v4.0.21006\aspnet_regiis.exe -i

HTTP Error 404.17 - Not Found - The requested content appears to be script and will not be served by the static file handler
The solution for this problem is available in the following web URLs. It normally occurs when you have not selected the right pool for your application. Application pools can be changed from advanced settings in IIS 7
http://www.gtrifonov.com/blog/2009/02/27/IIS_7_HTTP_Error_404_17_The_requested_content_appe.aspx
HTTP Error 404.2 - Not Found
The page you are requesting cannot be served because of the ISAPI and CGI Restriction list settings on the Web server.

This occurs due to the reason thatISAP or CGI resources are not allowed on the server. Following URL provides the solution in detail.
http://support.microsoft.com/kb/942040