I was just thinking the same thing. The only things I can think of are that it's a mistake on the website, or his phone went off. I'd been thinking for ages that Adams would have no trouble finishing that game off. Fritz agrees that Adams is massively winning. I think if there was something tactical worthy of resigning fritz would see it. I saw another mistake on the website in round 2 where it gave a losing move as the final move before a draw was agreed in Kramnik's game, so maybe this is just another error.
How did Michael Adams lose?

I definitely remember an error in an early round that made it look like the US Virgin Islands had actually won a game, so they do seem to crop up.
Someone on the Chessdom live chat said it was definitely wrong and Adams had won, but didn't say where the info came from.
Right, okay then. I'm thinking that Black resigned there, and they just got the result the wrong way around on the site. If his phone went off though, there will be some unhappy England team-mates (when Adams could have happily got a quick draw if he wanted).
Still, comforting to know. :-)
Was the result formally reported yet? It could be a mistake...
I was watching the match between IM Watu Kobese vs. GM Hikaru Nakamura one afternoon. It seemed that black had, with the last move, placed white into zugzwang and had secured the game. However, the game's result was listed as 1-0; USA was shown as having won the match 2.5 - 1.5, but Nakamura had apparently inexplicably lost.
I came back an hour later, and the result had been corrected, 0 - 1 with USA winning 3.5 - 0.5.
What happened?
What happened here for Adams? England were 2-1 up, needing only a draw to win the match therefore. Adams had 9min57 left, the Vietnamese player had 16min35. Adams played 71...a4.Then what happened? The result is apparently 1-0, i.e. a win for white. However, black is a rook for knight up. Admittedly, there are opposite coloured bishops, but Adams is definitely not losing. How could Adams have lost the game? Did his phone go off?