When I moved my blog to the new domain name, I also upgraded WordPress. I didn’t realize it but some of the setting were different that the previous version.
For some reason, this blog was set to require registration in order to leave comments. Once I realized that’s what was going on, I couldn’t figure out where to change it.
I have finally shut that feature off. Now when someone wants to leave a comment they can do so without registration. All comments will be approved before posting to weed out the spam.
Sorry for the confusion!