FileManager will refresh the host page when the session has expired or session is not found so it's expected behavior when Application Pool restarts. The reason it tries to refresh the page is that FileManager does not know or interested in your authentication mechanism; for example if you have a login page in your site FileManager will not know about it so it simply refreshes its host page expecting that your site redirects to your login page automatically.
So when you start debugging your project with Visual Studio (F5 or CTRL+F5), does the page load and refresh? This is not expected behavior, you should observe a refresh only if session expires or .Net AppDomain is restarted.