People have been having trouble posting comments as Blogger makes some changes.
My Blog Master says:
"I think it has to do with the new "beta" version of Blogger.
Some bloggers like myself have signed up for the beta version. I don't know how many have.
Maybe half? Anyway, I think they're having problems with communication
between bloggers using the "old" version and the "beta" version.
Here's the workaround. If you want to leave a comment on my
blog, go through the usual routine: find the page, open the comments
section, write your comment, THEN where it says "choose an identity,"
don't choose your blogger account, instead choose "Other." Enter
your name and website manually, and publish the comment as you