hi bruce, thanks for providing a crash id. unfortunately this crash is caused by trusteer rapport which is running on your device and hooking into firefox - please check that you are fully updated there or temporarily disable/uninstall that software for the moment.

please also get in contact with trusteer's support which are usually very quick to respond and fix issues like this: https://trusteer.secure.force.com/PKB/articles/en_US/FAQ/browser-crashes

Thanks for the rapid reply. I had already updated Trusteer, before posting here. I have now reported the issue to IBM and will wait for their response. In the meantime, I'm on Chrome.

Here's an update: IBM claims that there's a conflict with my add-ons, but the only add-on I use is the French language dictionary. However, just by disabling the dictionary the problem has mysteriously gone away. Go figure.