Web sites and Web applications depend on the availability of Internet Information Services (IIS) application pools. IIS application pools in turn depend on the Windows Process Activation Service (WAS). If WAS is not running or errors occur during the startup or shutdown of an application pool, Web sites and Web applications may not be available.
A worker process that fails to respond may exhibit one of the following symptoms:
Communication failure with WAS.
Worker process startup time-out.
Worker process shutdown time-out.
Worker process orphan action failure.
To diagnose a worker process that is failing to respond, refer to one or more of the following resources:
How to use the Debug Diagnostics tool to troubleshoot a process that has stopped responding in IIS
How to use the IIS Debug Diagnostics tool to troubleshoot a memory leak in an IIS process
How to use the Debug Diagnostics Tool to troubleshoot high CPU usage by a process in IIS