When you attempt to start the WWW service you get:
“Error 2148073487 object already exists”
No need to reinstall IIS just yet.
To fix it:
Go to %system root%\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\
(or %windir%\Profiles\All Users\Application Data\Microsoft\Crypto\RSA\ if it’s an upgrade from NT 4.0)
Make sure your admin account has full access to the “MachineKeys” folder (You might need to take ownership first)
Start your WWW service