"unable to contact ip driver, error code 5"

I have a new W2K8 server joined to my domain.  I have added a domain admin's account to the local group 'Administrators'.  It does not show but if I add it again it tells me that user already belongs to the administrators group.  I can log on remotely but can't do administrator tasks.  I get a 'You may not have the appropriate permissions to access the item.' when trying to run a command line as administrator.  I also see the 'Unable to contact IP driver, error code 5," error when trying to ping another server.  Logging onto the machine using the domain administrator account everything works fine.  This is some kind of authentication configuration?  Do accounts added to the administrators group not show as a security feature?  It seems to be there but doesn't have the rights to run as admin on the local machine.  Thanks for any tips experts...