its a server glitch on 343's end. far as I know when the servers start getting stressed they pick random accounts to put into a backup server for a random amount of time from a few minutes to weeks. only solution ive been able to find is removing your xboxlive account from your xbox and then recovering it without deleting any saved game info. other than that there hasn't been much if any info given out about it by 343 or Microsoft other than a post or two. and as far as Microsoft is concerned they fixed the problem months ago or so they said in a press release. occasionally it is for maintenance but for the most part at any given moment between a few hundred and a few thousand people are thrown into a backup server randomly for no discernible reason.