I've no idea how this is even possible or what can cause this. Few days ago I started to get error "Your Xbox LIVE membership information isn't valid. Please use a profile that contains a valid membership or recover your profile from Xbox LIVE." when I tried to log in on my Xbox. I've 11 months of live membership pending.
Then, I deleted my gamertag and tried to recover it, but after loading like 15 sec at screen "Recovering your gamertag... Please wait." (green bar doesen't move and it's stuck at ~10%) I get error "Cannot recover your gamertag." I went to my bros place and moved gamertag via usb-stick to my own xbox again, cause he could recover my gamertag on hes xbox, on hes house. But at my place, I get this error: "Your Xbox LIVE membership information isn't valid. blablabla" again.
Then formatted my xbox and thought that would help but nooo, It still gives me same error when I try recover my gamertag. Then I called to my bro and asked hes windows live ID & password to test that there is nothing wrong on my internet between router & xbox. And voala, I could perfectly recover hes gamertag on my xbox.
Wth?! Is my gamertag bugged or what?
short explanation: I can recover anyones gamertag on my xbox and log in live, except my own GT. And anyone can recover my gamertag on their console, except myself on my console. :(