Yeah... if you look at the list of last posts in here most of them are about login and changing worlds problems unfortunately :/
We have gotten answer from EA support that they don't even have direct support for CnC TA anymore, and this forum is the link between the players and Envision (owned or contracted by EA!?!) who are the tech guys and programmers of the game.
EA is responsible for Origin and therefore also the payment of credits in the game, and also login accounts... EA changed the login and this messed up something for the programmers at Envision.
Even though we have not gotten much detail or any probable time of fix for this they are working on it, and have said something about a timeframe of a week and that was 4-5 days ago now...
It is not in the list of fixes for the next update and that is probably because they are running the login problem as a separate case parallel to everything else (I am guessing).
This have been going on for several weeks now, and the tips change from trying Incognito mode, reloading the page with Ctrl+F5 to clear previously loaded page history, clearing cookies for *.EA.com and *.commandconquerer.com and to run CCleaner on your computer etc...
I had the same problem and did a lot of messing back and forth between different kind of things and got it to work after that, but I did so much nonsense that I can't give you a clear description of it.
Even though in the beginning even though I had problems on Chrome it worked fine on Firefox, but it began to be a problem there too the next day.
I have had it stable here for the last 4 days now, and the only difference now is that I can't have multiple accounts logged in so I have to use 1 account on Chrome and another in incognito mode or Firefox etc...
Envision have said that logging in multiple accounts is not a spec in the system and will not be made any attempts to make that possible either, as well as it's not wanted from EA's side to have multiple accounts logged in simultaneously.
If I hear of a definite fix that works and it gets verified by others I will post it here in this thread...
/Key