This is a problem with the old Go.com central accounts and the fact the difference services over time had different guidance for what to setup accounts as. The net result is if you have an account with your email as the username, not all sites behave equally. You could get things like it works fine in the local service, but when you goto edit profile things, it would switch accounts, etc. I had this problem before MM+ was around... between ESPN and club penguin I had problems. Trying to edit my profile would switch which account I was looking at compared to the account I had logged into ESPN with.
By contacting member services at ESPN, they were able to modify my account profiles so my username and email were not ambiguous anymore. ESPN changed my account username.. and things cleared up.