You are right in saying that: But what is the solution to this issue and I get an error when i connect to the web iSQL plus - i do get the same error-

ERROR - ORA-12514: TNS:listener does not currently know of service requested in connect descriptor

Results below from command prmpt:
=======================================
SQL> conn / as sysdba
Connected.
SQL> exit
Disconnected from Oracle Database 10g Release 10.2.0.1.0 - Production

C:\Documents and Settings\Nitesh>sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Sun May 13 15:44:01 2007

Copyright (c) 1982, 2005, Oracle. All rights reserved.

SQL> conn sys@orcl as sysdba
Enter password:
ERROR:
ORA-12514: TNS:listener does not currently know of service requested in connect
descriptor
==========================================