Thanks. Yes I do still run Snow Leopard, so I went with the 25.0, as you recommended, which indeed did the trick. Thanks, Avi, you really know your stuff.
When I go to the About window, it now reads:
25.0.1614.71 - Opera is up to date
However, I definitely recall the old 24.0 (and change) line also ending with the assurance "- Opera is up to date," which was obviously untrue. If not for that, I would have been savvy enough myself to have checked for the latest update my system could handle, and would never have brought my inquiry up here.
If that was a bug, or just semantic sloppiness, I do hope it has been fixed. Thanks again.