When trying to browse the Oracle server resources it may take a few minutes if there is no net service name entry whose name is ORACLE_SID in tnsnames.ora.
ORA-12154 errors are logged several times in the debug log.
 2014-02-07T17:21:13.401 [fsys\oracle] - OCIServerAttach() Win 1
 2014-02-07T17:21:23.837 [fsys\oracle] - OCI_ERROR: ORA-12154: TNS:could not resolve the connect identifier specified
 2014-02-07T17:21:23.837 [fsys\oracle] - OCIServerAttach() Win 2
Add net service name entry whose name is exactly same as ORACLE_SID to tnsnames.ora