My son has the same game. Similar things happened. The only thing that seemed to cure it was a clean OS reinstall. Game would work for week or two and then go weird again.
One day (bear with me) I mentioned he ought to stop using IE on account of various security issues and pointed him towards Firefox. Been a month now and haven't heard him screaming at the game. I still don't know what the real problem was. Ea website gave him and I both the run around, but removing IE6 from his system seems to have cured it. So far, anyway.