You have just installed CCS 10 or higher version of software. You are trying to connect to the web console for the first time after installing but instead the user receives an error message that the service is unavailable.
This error is generated by the W3SVC service, which is responsible for creating IIS worker processes to handle incoming http requests. When W3SVC fails to create a worker process, it will generate this error.
There are a number of reasons why W3SVC may fail to start an IIS worker process. These include invalid application pool configuration, failure to create the process due to incorrect application pool identity settings, bad IIS configuration that causes the worker process to fail to initialize, or a process crash due to application logic.
NOTE: Security settings are applied during the startup phase of any NT/2000/XP/2003 machine.