I'm running Windows 8 CR (64-bit) and I'm having trouble with LIVE now (for the first time).
When I try to login to live running either Flight or AoE: Online I get the following error message:
"The product key you provided has already been registered to another LIVE profile. Please enter a valid produce key or go back and choose a different Windows Live ID."
Problem is, I only have one Live ID and I used to be able to play both games using it. When I go to the games under GFWM I don't have a product key but I have a LIVE access code which shows up when I get the error message. I try to accept the terms and login with the LIVE access code but I get the same error again. I've tried downloading the GFWM client again as well as uninstalling and downloading/installing both apps using the steps provided in the technical support FAQ and still no joy.
The problem seems to be GFWL specific because I can log into other games (Batman: AA purchased from Steam) just fine.