Woah. Thanks for the heads-up. I'm unable to reproduce that in Chrome or Firefox but I'll look into it. I ran the Qualys SSL test on sequiturs.com just yesterday and got an A+!

EDIT: I encountered a transient NET::ERR_CERT_AUTHORITY_INVALID a while back as well, actually. I've just replaced the Comodo cert I was using with one issued by Amazon. Would be very interested to know that it works for you now!