The Windows Process Activation Service has encountered an error during the SID mapping for the application pool '%1'. The ...

The Windows Process Activation Service has encountered an error during the SID mapping for the application pool '%1'.  The application pool will be disabled.  This typically happens if there are more than one application pool name that maps to the same SID.  To resolve this issue, please change the name of the app pool and recommit the configuration changes.  The data field contains the error number.