ASP.NET web form not responding :(

Question

Hello everybody!

I have a very frustrating problem with ASP.NET pages. I have a web form with a ScriptManager, an UpdatePanel and a few buttons in it. When I let the web page idle for a few minutes and push a button, the server seems to stop and refuses to respond. The browser keeps trying to get a response but finally I get a timeout error saying that the connection was closed. This error happens only if I have anonymous authentication enabled. With windows authentication the page works fine.
Has anyone ever had this problem? Is there something wrong with ASP.NET AJAX? Does IIS need some additional configuration? Please help !