Use Performance monitor -> ASP.NET -> Application restart counter on daily base.

Application recycling is common issue in the newsgroups. Most of the time programmers notice that the session lost due to application recycling but some times just application restart noticed. There are many causes to application recycle, the most common are:

1)      Unhandle Exception.

2)      Any write to application bin directory.

3)      Any change to web.config.

4)      Anti-virus program that touch files.

5)      One of ProcessModel attribute in machine.config that cause application recycling.

To monitor that behavior as it started it’s highly recommended to monitor Use Performance monitor -> ASP.NET -> Application restart counter. Finding high value in that counter might help you to find and fix the problem ad it happened rather then look for it when the application already running.