Marco,
That was exactly what the problem was. I had seen the statement about the directory having () in the name while browsing the forum, but I thought they meant in the Oracle client install.
Thank you very much for your quick and accurate response.
Paul
PLSQL Developer Sign-on data
Username: ifsapp
Password: ifsapp
Database: PAUL_RACE.WORLD
Connect As: Normal
Fails with the ORA-12154
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Connecting with SQLPlus
sqlplus ifsapp/ifsapp@paul_race.world
SQL*Plus: Release 10.2.0.4.0 - Production on Wed Dec 23 11:30:53 2009...