Thanks for the help.
Here's a tip for the developers, when you display system info in the about box, make the text selectable so that it can be copied and pasted into a post or email instead of having to do a screen capture.
Yes, I have build 288. I didn't have multiple instances open -- the things I referred to were done consecutively.
I'd uninstall and reinstall, but I worry about hassles in getting all the settings the way I want them, and that could be more trouble than dealing with the crashes.
But I take it, at least, that this isn't a common problem with a known solution.