WordPress recently updated their commenting system to force people who enter an address associated with a WordPress/Gravatar account to sign in.
Unfortunately, I have no control over this. Please see the article here, which contains a link to reset your password if you’ve forgotten it. Apparently this “improvement” to the comments function was a knee-jerk reaction to placate a certain VIP who was apparently having his identity forged on comments. As the article shows, though, it’s still easy enough to do without this stupid change.
What’s really irritating is that you cannot delete a WordPress account – so if you ever signed up for one (or for a Gravatar) using your email address, even if you never had a blog, you are still going to be required to log in.
However, at long as you enter what appears to be a valid email address, you can still comment – it doesn’t have to be valid. I’m going to suggest entering “wp.” in front of whatever your real email address is. If I see that, I’ll know to remove it for any replies.
For example: instead of firstname.lastname@example.org, enter email@example.com
I’ve also modified the settings so that you don’t need to enter an email address at all. (But please leave a name, so I know who you are!) I may have to change that back if I start getting too much spam, but at least it will be another option for you.
Sorry for the inconvenience!