I remember having this problem when the game FIRST came out, and i was the one who posted the solution
I'm not sure if it still applies to your issue or not.
But when tons of us had this maint screen issue, it was due to blocking cookies on Internet Explorer.
check your cookie settings and make sure it's not set to block all cookies.
open IE, go to internet options, privacy tab, click advanced button, accept cookies.
might want to also go to the general tab and click delete, and clear out temp files as mentioned, and include cookies