解决方案来自：
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=240301&SiteID=1
USE aspnet_regiis -i
DETAILS:
If you're like me and have both
ASP.NET 1.1 and 2.0 on your machine (along with the associated Visual Studio
2003 and 2005 products because you can't help but write software in both
environments) you may encounter this issue. Upon running your website
(via http://localhost/xxx or something like that), you may encounter the error page
that reports:
Failed to access IIS metabase
If so, you may have installed IIS
after installing the .NET framework. If that's the case, try running to repair
your ASP.NET installation and set up all of the appropriate ISAPI extension
mappings.
aspnet_regiis -i
If, however, you're like me and had
IIS already installed, and you installed VS 2003 and then VS 2005, and then set
up a 1.1 virtual directory / website, simply check that the appropriate ASP.NET
version is associated with it (Select VDIR --> Properties --> ASP.NET
tab).
"aspnet_regiis
-i" once again was successful! However, the directory it is located in was
not included a system path previously, so just note that you may have to run
this from the "WINDOWS\Microsoft.NET\Framework\vX.X.XXXXX" directory
(with the X's being your version number)