ORA-12154: TNS:could not resolve the connect identifier specified on Win2008R2 Instant Client

I am seeing very flaky behavior from the client where intermittently I can't connect to the DB services via sqlplus - its throwing error ORA-12154. The service can be consistently accessed from the local (non-client) nodes

Here are the .ora files I had created during the configuration:

C:\app\administrator\product\11.2.0\client_1\network\admin>dir
Volume in drive C has no label.
Volume Serial Number is 58B5-EF5C

Directory of C:\app\administrator\product\11.2.0\client_1\network\admin
03/02/2015  04:31 PM               356 listener.ora
03/05/2015  04:43 PM               466 sqlnet.ora
03/05/2015  04:54 PM               506 tnsnames.ora

Here is sqlnet.ora

# sqlnet.ora Network Configuration File: C:\app\administrator\product\11.2.0\client_1\network\admin\sqlnet.ora