One or two people have mentioned problems they are experiencing in that they can post comments on some blogs but not on others.
I have had the same problem for the last couple of days. You type a comment, try to post, it asks you for your ID...you click "google account"...you get sent to the google log in page and log in...you go back and try to post your comment and it just keeps sending you back to Google log in on a loop. So frustrating!
I have spent hours trying to find a solution on Blogger Help. I've cleared the cache (even though I don't really understand all that stuff), deleted cookies and browsing history, and followed various other instructions...but to no avail.
At last I spotted a comment from someone who suggested it may be an Internet Explorer problem, so I've changed over to Firefox browser...and guess what? It works!
Maybe some of you are already aware of this, but in case you aren't I thought it would be useful to share this info.