This Also Happened with me, But I don't have Vista, Both my computers were doing it and Me and my friend were playing and we get Dc'd at the same time.
I've got the same problem, but the problem appeard right after I install'd toribash 3,5. I have 3 computers, windows xp on two and vista on one, all of them got the same problem, so I guess its not about the operating system.
Same problem here, I keep getting "Not connected" mid-fight.
And when I'm joining or creating a game, I have to join twice, the first time I always get "Not connected" but the second time always works.