Have you restart the vCenter Server service?
It's seems that your vCenter is not in a AD domain.
Maybe you have register all the plugin with the IP address. In this case you have to modify several *.xml files to fix the address.
Or simple reinstall the vCenter Server (or upgrade to U1) choosing the existing DSN for the DB connection.
Andre
Andrew | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro