You get this error:
HTTP Error 503. The service is unavailable.
The application pools were failing to start as they were not able to login using the proper account. Here is the error:
Application pool plesk(default)(2.0)(pool) has been disabled. Windows Process Activation Service (WAS) did not create a worker process to serve the application pool because the application pool identity is invalid.
Reset the password on the two accounts:
Then reset the login creditendials for the two application pools. The application pools started and the sites are working again.