Can"t turn on Vista feature "IIS Metabase and IIS6 configuration..."

Env.: Vista Ultimate / IIS7

I'm trying to turn on this feature in the Control Panel. After a few
minutes, I receive a very generic error message. The event log contains 500+
(!) error messages (Events 4375 & 4385).
I tried several times, rebooted each time, to no avail :-(

All other features can be turned on just fine.
I uninstalled (sorry, turned off) all of IIS, rebooted, reinstalled
everything. It failed again :-(

Unfortunately, my Vault Server needs this feature!

Please Help!
TIA,

Serge.