As I already mentioned, that error means that the client is looking for a listener where the listener is not present.
That would mean
1) The client looks at wrong place (host/port)
2) The listener is not working

Please let us know
1) From which machine you try to log
2) Look at the tnsnames.ora and see if the address of this listener is present there, coresponding to your connect string
3) Look at the sqlnet.ora and see what the policy is (should be try all addresses until one succeeds or something)
The Oracle Net Assistant also has interface to these files.
The listener.ora file does not seems to have any problems

Regards
Boris