The Application Object Server instance that is specified by the current client configuration could not be found. Contact ...

The Application Object Server instance that is specified by the current client configuration could not be found.
Contact your administrator to resolve this problem.
Hint to the administrator:
1) Check spelling and correctness of host names and IP address masks in the client configuration.
2) Check availability of specified host. Is it turned off? Can it be reached by client's network services?
3) Are host names being used without having properly working name services on the client?