Here is the solution for the error "Failed to access IIS metabase." which occurred in my case when i was trying to access a web application first time after installation of IIS (Version 5.1) in my XP pro.
In command prompt, go to the location:
Run, aspnet_regiis -i
This will install asp.net 2.0. & web application works for me now :)
At times ASPNET account may not have permission to access IIS metabase.
The following command has to be executed;
aspnet_regiis -ga ASPNET
Hope this should be helpful :)