Just made a small, 64-bit app with just the OracleSession component. I added a button which executed the LogOn code shown in the first post. It connected fine. I tested both from within the Delphi IDE, and running the exe standalone when Delphi is NOT running. Both connected fine.

I also checked that when I load my DLL project into Delphi, I can go to the OracleSession component and check the 'Connected' property, and it connects fine there. (Although I do normally develop with this NOT checked.)

As a final test, I completed exited Delphi. I ran Excel with my DLL. When I try to connect to Oracle, I get the AV.