Hard to say.
It looks like not all parts of Instant Client can be located properly.
Is there any other Oracle software installed on the machine?
Does a connection with sqlplus work?
Do you connect via ODBC?
Is the Instant Client directory in PATH?
Is there a OCIW32.dll on your machine somewhere outside your Instant Client directory?
I am having Windows server 2008 64 bit, oracle 11g (184.108.40.206.0) and oracle thin client 220.127.116.11.0. Getting the error error while trying to retrieve text for error ora 01019 when i try to connect through delphi application. But database connection is successful through PL/SQL Developer. I have checked TNS entry, ORACLE_SID, ORACLE_HOME environment variable.