I was chatting with Xbox support today and they asked me to talk also to windows support. After chatting Windows support they suggested I post my problem to Xbox Forums ... so here I am.
I have odd issue with my account - In Xbox 360 all is fine, I can log in anytime with no problems, but with Windows 8 games, sometimes game logs into Xbox fine and sometimes it gets stuck in "logging in" prompt and never gets a timeout or error message. The Windows 8 Games app seems to be always able to log in, but games sometimes log in and sometimes do not.
I found some article that this might be happening if account is in one country and user in another Country, or if the timezone is incorrect.
I am located in Ireland and my account is set to be in Ireland ... Windows locale is also set to "English (Ireland)" ... so this "should" not be an issue here.
The account has not always been an Irish account. It started out as Finnish account, then was UK account for some time before final movement to Ireland. I did the account location swap from UK some time ago (cannot remember when exactly) - could this be causing it somehow? A side note - I sometimes end up at /en-GB/ pages instead of /en-IE/ pages at xbox.com or even http://support.microsoft.com/?ln=en-gb