Storyline 360 crashing when I try to add a character

Hi folks,

This hasn't happened to me before today but it's nonstop now and I basically can't make any progress.

Almost every time I go to add a character to a slide the program freezes and I have to use Task Manager to get out of it.  Needless to say, if I haven't saved in the last 10 minutes it's sad times.

As well as freezing when I add a character, it also shows a wee red X and part of a word, which I think is the character (but isn't). It isn't expandable or closeable (because the program has always frozen at this point). I've attached a screenshot. "Lydia" was already there -- she's not the one I was adding.  I'd welcome any suggestions because I'm losing my mind.