The problem is you changed your email address on a different machine or browser but you still have a persistent login cookie in Chrome that corresponds to your old user. So it sees you as authenticated but it doesn't find your user since it doesn't match anymore and it causes this error.
If you click the Sign Out link at the top and then login again it should work fine.
I'm adding logic for the next release to automatically redirect you to the logout page if it detects this condition.
Hope that helps,