The client is microstation (CAD application) on Windows NT workstation connecting to an Oracle 8.0.3 database. All other systems connect OK, but this one system.

I have checked...

1. ping - no request timed out
2. tnsping - no problem
3. client trace - nothing amiss in these trace files

Any other ideas to solve this issue?

BTW, sqlplus from this problem client connects without any problem to the database.

Thanks.