I seem to experience some problems with WordPress. To be more specific the problems arise when I am trying to post a comment or click like on blogs that are under their own domain (blogs that have an example.wordpress.com adress are fine). Here’s a screenshot of the error message that I get:

That email adress is associated with an existing WordPress.com (or Gravatar.com) account. Please click the back button in your browser and then log in to use it.
That email address is associated with an existing WordPress.com (or Gravatar.com) account. Please click the back button in your browser and then log in to use it.

Of course I am already logged in and the email address is mine.

A similar thing happens if I want to click “like” on a post, I’ll be asked to log in (again: blogs that have an example.wordpress.com adress are fine). After I’ve clicked like & logged in, nothing happens. So I click like again, and I’ll be asked to log in again.

Here’s a screenshot from RobertSantafede.com:

Just one more step to like this post (but you'll have to repeat this step forever and ever like Sysifos).
Just one more step to like this post (but you’ll have to repeat this step forever and ever like Sysifos).

At first I thought the errors was related to my browser, so I decided to try commenting with Chrome instead of Firefox, but had no luck…

So, after having read about this on the WordPress forum (http://en.forums.wordpress.com/topic/recent-update-to-commenting?replies=4) I now believe that the error is to be found here:

Update #2
We discovered another bug that prevented some users from commenting if they attempted to comment on a blog with a custom domain name and had third-party cookies disabled. This bug has been fixed as well and we’re sorry for any inconvenience this might have caused.

According to user johnnytesting “It’s to stop counterfeit commenting. It may have been implemented poorly, but it was needed. Previously, if I had timethief’s email address, I could pretend to be timethief. So now, if someone tries to comment with an email in the WP database, WP wants to make sure it’s legit. That’s all.”

But, the problem still remains and as I discovered; multiple posts have been made on the subject.

http://en.forums.wordpress.com/topic/you-must-be-logged-in-to-comment?replies=185
http://en.forums.wordpress.com/topic/about-the-recent-update-to-commenting?replies=5