Later that evening, a host migration went weird, my gamertag dropped out of the game, but I was still playing. As Aquasomeoneorother. With a completely different loadout (that I've never used!). Grenades weren't exploding, I was seeing 3 of the same player, all kinds of wrong. So dashboarded lest anything terrible happen.
Checking XBL service status this morning though, and at time of writing they've got:
Service Alert
We are aware of the problem and working to resolve the issue. We apologize for any inconvenience this may cause and thank you for your patience.
(http://support.xbox.com/en-gb/pages/xbox-live/xbox-live-status.aspx)
Posting for awareness... typical Microsoft, a technically valid piece of information but contextually useless. What problem? What's the issue? Tw@s.
Edit: I wonder if XBL is being attacked... Friend of mine just reminded me that yesterday he logged into his xbox with auto-sign in and connected to XBL as someone else, not even in a game.
Hmm - further digging:
http://news.teamxbox.com/xbox/24144/LulzSec-Reportedly-Targets-Xbox-Live-Account-Info/