I have not been able to log in using my gamesas account for I would get the message 'incorrect login details...'

I went to the gamesas website and changed my password only and saved.

I logged out of the gamesas site, went to my homepage, then used tools- internet options- and deleted my browsing history.

I went back to the gamesas website and logged in to make sure new password took, it did.

Started Crysis 2 and used the new password and it passed. Played a muliplayer game, logged off and logged in again and it work.

Something to try. Goodluck!