IIS or send alert to

The IIS sotp with no reasons ,even in the event viewer their is nothing ,so I have to restart the service manually,my qustion is:
1-any body know a bout this problem of IIS.
2-if not I would like t recive alert if the IIS stopped so I know that I have to restart the service ,How can I manage this (sent alert to user ),I have Back office small Business server.