Can't start IIS "World Wide Web Publishing Service" Error 126

Keywords:
Could not start IIS "World Wide Web Publishing Service" "Error 126"

Problem:
Trying to manually start the WWW service for IIS gives the following message:
"ERROR 126: The specified module could not be found."

The "World Wide Web Publishing Service" goes back to a stopped status. While this service is stopped, in the IIS Manager, the Web Sites folder is marked with an X and none of the Web Sites can be started.

Solution:
Need to check the Event Logs (Start > Programs > Administrative Tools > Event Viewer)

Clicking on the Application section shows a number of Errors. The most recent two errors were the most relevant:

• Could not load all ISAPI filters for site/service. Therefore startup aborted.


• The HTTP Filter DLL C:\[path to a DLL that no longer exists] failed to load. The data is the error.
  

I had to go into IIS Manager. View the ISAPI Filters (right click the Web Sites Folder > Properties > ISAPI Filters) and remove the filter that was referencing this DLL.

Going back to services, the WWW Publishing Service then starts fine.