You apparently use the "COIV4.0.1+" version. That one has a few issues with duplicate prefs items, both absolute and relative paths to rom file and keycodes file.
You will need to correct that inside the "Classic" application:
- Right-click (or control-click) on "Classic" and choose Show Package Contents from the contextual menu. The content of Classic will be shown.
- You will see an item "COI"
- Right-click (or control-click) on "COI" and choose Show Package Contents from the contextual menu. The content of COI will be shown.
- You will see a file "hih1"
- Double-click hih1. It will open in TextEdit.
- Carefully remove the first two lines:
The top line should now be:
- Close the file and save the changes.
- Close all windows.
- Finally, run "Classic" once.
After that it should work as I described above.