So, my father was complaining about browsing being slow, and I took the opportunity to update his browser. Along the way, I got a dire warning about Adobe having released a new update to Flash Player to fix some serious problem (Adobe has released a critical security update for the Flash plugin.), so I downloaded the update (10.3.181.34).
And none of the flash-based games my father plays worked. Primarily, these are crosswords, but also the Jumble - and in none of them could you type the letters. On most, you could type one letter, but in a few you could type one letter and then all the other squares filled in with a one-up number sequence. This regardless of which square you started in or which keys you hit.
Well, what's the point of having Flash if it's not going to work? I hunted around the net a while, including at Adobe's support boards, and the only non-Ubuntu or non-Windows 7/IE 9 (my father still has XP) solution I found (the Ubuntu one I didn't get into, the Windows one involved setting ActiveX permissions) was a guy who reverted his system.
So I did that, and then found a nice site (www.oldapps.com/flash_player.php) where I could download the latest-but-one Flash Player ((10.3.181.14).
Playing problem solved. Crosswords are again doable. I just wish I understood what the problem was...