Maybe I can help. I had similar problems with service. Occasionally, service stop working. Better say, responding. After months and months of examinations,
I realize that service stoped to response in one condition:
If service is on server, and if that service is logged as some account, for example Administrator, and if someone else, in my case myself, use that account to log on server via RDP, after logging of the RDP session, the service stop to respond. I create for that service another user account, just for service himself.
After that, never saw my service(s) stoped responding.
Edit: maybe you use one account for your service, and for some scheduled task, like backup or so....
Just my thought.
Regards, Oggy