This error was happening when I first tried using ASP.NET on the XP Machines we have in the office. I tried adjusting the permission using MetaAcl Tool, but that did not do it for me. After further research on “Failed to access IIS metabase” error it appeared that when .Net is installed prior to installing IIS this error will occur.
To fix the problem, just run the following command to reinstall APS.NET and reupdated the permissions:
%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i
If that does not work, you can try adjusting the permissions as shown in the following Microsoft article: