The worker process failed to initialize the http.sys communication or the w3svc communication layer and therefore could not be started.

The worker process failed to initialize the http.sys communication or the w3svc communication layer and therefore could not be started. The data field contains the error number.

On one of the customer’s server we got this error while navigating to a website. Ours is a WebClient application and we use the ClickOnce technology to publish our files to the Server.
Recently there was an upgrade happened on that system. The system was running Windows 2003 Server with Service Pack 2. It was to be upgraded to Windows Server 2003 Enterprise Edition. Unfortunately, the upgrade was not successful and in the process the registry got overwritten. IIS too get corrupted. The website was running IIS 6.
IIS 6 has Application Pool; an Application Pool can contain one or more applications and allows us to configure a level of isolation between different Web applications. Each application Pool has its own Identity. Usually, it runs with the Network Service credentials.
The Problem:
Whenever we tried opening a web site we were getting the “Service Not Available” screen. The reason was the application pool would automatically get stopped. Event Viewer was displaying the above error. Please refer to the article below for further reference.
http://support.microsoft.com/kb/896286
Troubleshoot:
We tried the above steps mentioned in the article but unfortunately it didn’t worked out. We also referred to the below link which mentioned about an issue with one of the service pack 2 updates. Please refer the article below.
http://www.pmcdonnell.ie/?p=42
None of the above resolution helped us in resolving this issue.
Following are the steps that resolved the issue.
1. Uninstall IIS
2. Re-Install IIS
3. Run the below command. If IIS is installed after .Net then we need to register the asp.net. Open the VS command prompt or go to c:\[windows/winnt]\[Microsoft.Net]\[Framwowrk]\[ v2.0.50727]\aspnet_regiis.exe –i.
4. Create the virtual directory.
5. Create the Application Pool.
6. Assign the application pool to the virtual directory.
7. Run the website.