Configuring IIS Express failed with the following error:
Unable to access the IIS metabase. You do not have sufficient privilege to access IIS web sites on your machine.
The root problem was that the "My Documents" folder had setup to be on a network share, and the share was not accessible. Once I changed the "My Documents" folder location to a local folder (by modifying the registry value), it started working again.
Changing this key worked for me:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\Personal
I know that this may not be a common scenario that you might run into, but I've posted it here because it gives the same symptoms.