I have been struggling to get around what I thought was a bug of the excellent Windows Live Writer; when trying to publish a post to my Blogger blog, I would get the above error message.
After reading dozens of fora, Q&As, and finding complicated solutions, patches and the like, I added the program to Windows Firewall as an exception and it works.
If you have been having my same problem, try for the simplest solution first before tampering with code!
