You mean the purple Application Started event? That, from my understanding is the site starting up after -
> someone comes to visit after a period of inactivity
> site starting up again if app pool has been recycled
Perhaps you need to look at the application pool and make sure it's isolated - eg.. not with other website instances. Sometimes you'll find that you reach a critical point where a website needs it's own application pool to stop it from constantly recycling because it's exceeded the memory set for it. That is different to the time out pool where the time out can be caused for many reasons from a code point of view.
If IIS has been restarted, reset or changed in anyway, it will force an application Started event on all websites.
The event viewer displaying that message as well has nothing to do with the scheduler -the event viewer is simply telling you of events that occur, like logins, errors, new users, alerts.
It is not really an 'error' what you are seeing, merely telling you that for some reason, usually a site visitor or app pool being reset has occurred.
I could be wrong but I look at these as well as our server logs on a regular basis and that is my own conclusion.
Nina