I recently re-installed Windows live Mail 2011 for my account with Comcast following these instructions from Comcast.

http://customer.xfinity.com/help-and-support/internet/connect-on-window

It worked.

I can now send and receive with no problems.

Since the install brought-up my prior account information I deleted that account, re-stared the computer , and re-created the account with the instructions from Comcast.