I am experiencing this problem, too:
I'm unable to leave comments on my own blog (yikes!) without being logged in (error message: You must be logged in to comment with that email address.), and some of my readers are blocked, as well.
I have my comments set as open to anyone (i.e. don't need to leave an email address).
Thanks for looking into it! (^_^)
The blog I need help with is hbdchick.wordpress.com.