Personal firewall stops Spotlight traffic and Error received:
"can not resolve host name"
"ORA-12541 TNS: no listener"
When running Spotlight and a personal firewall on the same computer user must either turn off the firewall while using Spotlight on Oracle or reconfigure the firewall to allow network traffic (both send and receive) for Spotlight on Oracle.
Other suggestions for ORA-12541 - TNS:no listener:
Check that the listener is up and running with lsnrctl command within the DOS prompt.
1) After comparing the local Tnsnames.ora with the server's Listener.ora, check the C:\Oracle_home\Net80\Admin\Tnsnames.ora file is configured correctly [e.g. valid Alias, HOST, TCP Protocol, and SID name].
2) Tnsping the client to db server.
3) Check the Oracle Home path for the Oracle instance within the resgistry.