This service, from my understanding, is responsible for the live tiles on the start screen. By default it is running. However if there is no interactive logins then the service isn't doing anything so it quite possibly shuts down (probably after idling for a while like a website does). It will start up again when an interactive user logs in. I would recommend you take a look at the event logs to see if you can see a corollary between user logins and the service starting.
Note that the service, on a server at least, probably isn't that useful and can be disabled such that you won't have this issue. You won't have live tiles anymore but I'm not aware of any other issues. So that would potentially be an option as well.