> Is there an app stealing focus.
That triggered me to unplug the VirtuaPin interface, and then it came up. So that's what's stealing focus. I had wired the coin door switch to be insert-coin (as the actual coin mechanisms have been removed), and that appears to have been a mistake. Using the VirtuaPin controller app, I can see that input is always on when the coin door is closed. Oops.
Will come up with another insert-coin solution. Thanks! It also took me a while to realize I had to use L and R arrow rather than U and D to navigate the menu, so can quit normally now. Appreciate you asking good questions!
Irony of the day: my cabinet is a repurposed Williams Road Kings, one of the samples.