Is anyone else having the same problem?

Tedious query here, but Blogger is not letting me comment on this and other Blogspot blogs. I know some of you can still comment on this site, so I'm at a loss to see what the problem is.

Obviously if you can't leave a comment, I can hardly ask you to let me know. But if you can and have an idea what it may be, do let me know (in clear, idiot-proof language, if possible).