Today it happened on a different web site, convincing me that the issue is at my end. I'm going to guess it might be my ten-year-old computer and 6-year-old OS having trouble keeping up.
I've considered getting a new computer, but my old one works fine for what I use it for (email, weather reports, chat boards, the occasional snail-mail letter, journal, a few web sites, and pics.) The games I play (chess and solitaire) don't require a lot of processing power. And when I go on-line window shopping for a new one, and look at the prices with the fanciest screens, which I'd want, the prices are high. You look at (e.g.) an $800 computer, but then you want more RAM, and then you want a solid state HD, and then you want a bigger screen, and then you want more pixels, and pretty soon you're looking at a $2K machine and reflecting on the fact that you don't really need a new computer at all.