I found a message on blogger help group but i couldnt see how i could reply to you, so thought i would try here!

I had the same problem not being able to leave comments on others blog. In the end i clicked on the bit where it says create google/blogger account. I did this, and there was a part in there saying sign in as my username. i clicked and it redirected me back to the comments page with my user name on there, and all was fine.

You prob got an answer from centre by now but thought i would help just in case!

Tina from
http://mummydiariescouk.blogspot.com