I am having the same problem. I have also searched www.ads-software.com and there are many other questions similar to this that are never sufficiently answered, or answered at all.
I have migrated some posts / comments to a new blog. Changed the author name and email, set up a new gravatar, but nothing changes.
I did find one blog that talked about the database cache needed to be cleared (not the browser one) but cannot find any clear instructions.
Apparently,y even though the email and name is changed the comment user id is the same in the database and that is what the gravatar is attached to. Does that make sense?
So, how do we delete or change the comment user id?
