Access Denied

Hello, I have a domain user account which we've assigned it to the Local
Administrators group on a w2k3 server machine in trying to allow this user
to access and administrate the iis 6.0 manager. But when this user opens
the iis manager console and tries to expand the local machine name it
displays 'Access Denied' pop up asking for User Name and Password. We
supply it the correct account info and then it displays 'You have been
denied access to this machine'. Would anyone know why it's not allowing
this user to access the iis manager even though he is listed as part of the
Local Administrators group?

Thanks in advance.