I got a new laptop recently and tried to setup IIS and transfer existing sites to it. The laptop had typical Windows XP Pro setup with IIS 5.1, Visual Web Developer 2005 Express Edition and Microsoft .NET Framework 2.0 installed.
The sites were copied over and set to use ASP.NET version 2.0.50707 but when launched IIS generated the "Failed to access IIS metabase" error. Poking around on the internet I found some articles referring to things like granting permission to specific user accounts and re-registering ASP.NET... but none of these worked.
I even tried setting up a brand new website and still got the same problem. The only thing that worked was running the web apps as File System but that's not how I want it done.
While poking around with installed components (in Add/Remove Programs) and IIS settings, I suspected that the Microsoft .NET Framework 2.0 got corrupted so I reinstalled it.
Once the framework got repaired, all websites functioned the way they were supposed to. Hope this tip will help you solve problem.