An idle component on the status screen typically means that one of the IIS webapps is no longer running. Each of the IIS webapps regularly update a timestamp in the database to indicate when it was last running. IIS automatically stops webapps when they are idle and starts them again when required so you can often see the components showing as idle on the status screen if there is not much activity. However we have seen an issue where IIS was not updating correctly.
RESOLUTION: Restart IIS