提问：Server Application Unavailable
在IIS中运行ASP.NET 2.0程序时出现如下错误：
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.
以下是错误日志的内容：
aspnet_wp.exe could not be started. The error code for the failure is 80004005. This error can be caused when the worker process account has insufficient rights to read the .NET Framework files. Please ensure that the .NET Framework is correctly installed and that the ACLs on the installation directory allow access to the configured account.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
请问是怎么回事？该怎么解决？
ＰＳ：Win XP sp2，IIS5.1，ASP.NET 2.0（之前安装过ASP.NET 1.1）
该问题在CSDN的帖子是：http://community.csdn.net/Expert/topic/5335/5335588.xml?temp=.8805963
