ORA-12641: TNS:authentication service failed to initialize

I'm flying blind here, as I don't have the SQL*Net docs yet (v2.3).

I can connect to the database (7.3.3) with SQL*Plus 3.3.3 if I issue:

      sqlplus username/password

but if I type:

      sqlplus username/password_at_service name

I get the error.

tnsping is able to see "service name."

Any ideas welcome!

-- 

Dave Brady                    FAS Computer Services
Sr UNIX Sys Admin/Programmer  Harvard University
brady_at_fas.harvard.edu         LL1A Science Center
Phone: (617) 495-1273         1 Oxford Street
FAX:   (617) 495-1210         Cambridge, MA 02138