Removing Flash and reinstalling the new 10.1 version made no difference, it still crashes with an apparent font-related error. As an experiment I'll leave Flash turned off permanently and see if I get any crashes. I'm beginning to think that Flash isn't the culprit but it would not surprise me to learn that it uses whatever uncommon font or webkit font rendering code that's causing the crash.
Besides that I don't know what else I can do. Any other suggestions?