Oh, those things where you study the distorted letters and numbers in one box and type your best guess into the other. I've often found them tricky. At some sites I've known them to make me choose between an "O", an "o" and a "0", or a "1" and an "l", in a "font" (if it can be called that) where there wasn't any clear difference, or not to let me in even when I was confident I'd read everything correctly.

Some of the better implementations of that feature offer ways around it, like clicking somewhere for a fresh set of distorted characters or clicking somewhere else to hear them read to you. If it's one of the blogs I'm thinking of, though, there's no obvious way around that pothole so all you can do is come back later and hope it offers you an easier target.

I've never had a PC blog so I don't know if there are settings for blocking certain responders, nor what the responder would see if there were. I guess you could find out by starting your own blog. I don't know what the rules are about blog duels -- posting your comments in your own blog and linking them to the one you're replying to.