I switched yesterday from NPAPI to the PPAPI flash plugin without any problems. Working fine so far.
You might consider to uninstall the NPAPI flash if PPAPI is working fine for you. You can see the detected plugins here (click on show details at the top right corner):
Nevertheless Opera wouldn't load both plugins, but prefers PPAPI as far as I know.
I tried this too, but it has brought no joy.
It is so strange. I have a flash game open in one tab right now and when I go to this tab to type this message, it is as though my game is paused.