服务器同时安装并运行.net 1.1 和 .net 2.0 两个版本，突然出现错误提示：

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.

Administrator Note: An error message detailing the cause of this specific request failure can be found in the application event log of the web server. Please review this log entry to discover what caused this error to occur.

解决办法： 在IIS中新建一个应用程序池,叫"ASP.NET2.0"，然后选中那个网站的虚拟目录，点“属性”－》在“应用程序池” 中选择刚才新建的的应用程序池，点击“确定”。