I can connect to my 8i and9i databases with the EXTERNAL command which is suppose to be OS Authentication. But when I try to connect on the 10g database I cannot, and only get an insufficient privilege error.
User ID not set up for OS Authentication in the specific database.
Verify user set up for the database that you intend to log into with OS Authentication. OS Auth users need to be set up for individual databases if you wish to log in in that way, using EXTERNAL in Toad.