I shut down HTMLValidator 9.0302. but it kept running. Further it started spawning multiple copies of itself. It had about 5 instances going before I could kill it. It filled the screen with blank error dialog boxes, then when I clicked them, sometimes they would fill in with text.
I have attached a screen shot of part of the carnage.
I did a recently changed check, then edited two files that had errors. certificatewhere.html was not among them. It is a bit of a weird page. It tells you where you can download root certificates for various vendors. see http://mindprod.com/jgloss/rootcertificate.html
that includes this html. Sometimes the Certificates for those pages themselves are unknown, expired etc.