Consider the following scenario. You have Microsoft ASP.NET 1.1 and Microsoft ASP.NET 2.0 installed on a computer that is running Microsoft Windows XP Service Pack 2 (SP2). Then, you upgrade the computer to Windows Vista. In this scenario, you receive the following error message in the Web browser when you visit a Web page:

Server Application Unavailable

The web application you are attempting to access on this web server is currently unavailable. Please hit the “Refresh” button in your web browser to retry your request.