I, too, have a "problem face" or maybe it's more of a problem default expression. But it's not angry, it's apparently more of a pensive/unhappy expression--I mean, according to the responses I get from it, when I'm just going about my life as usual. I've actually had a person say to me, "You look like you just lost your last friend," when my day was really going pretty well. The funny thing is that I'm generally pretty happy-go-lucky, so it's odd that I have such a face. Hereditary, I guess, as Squeaky said.

But it does keep me alert to the possibility of reading people's expressions wrong.