I've tried 2 consoles, and deleting the gamertag and then recovering it. Basically, it works offline, but the moment I sign on to XBL with the GT, as it's loading the dashboard (and all that is visible is the spinning loading icon), it suddenly just freezes.
I've never modded my console, nor played any modded games, nor done anything illegal with my gamertag. My gamerscore is still intact, so I haven't been wiped or anything of that sort
Edit: Wow... what the heck. It even froze after I downloaded it onto a brand new HDD and new console. What in the world? I don't even know how the heck this works, because I can play GFWL games just fine; login and all.