Have been visiting other Blogger posts and enjoying them, but find it so frustrating not being able to comment. Wish they would fix this issue quickly.
I did find out that if the comment is embedded below the post with a "select profile" section, it doesn't work and makes you sign in over and over with no results.
By changing my settings to a pop-up window with a security word it worked well and I was even able to comment on my own blog. If bloggers aren't commenting try this change until the other is fixed.
Blogger has been working on this since May 24--hope it won't be too much longer.