More or less how my 60(7) barb died in A3 inferno; there was a massive (and sudden) lag spike of over 2500. Same way my 60 (9) wiz died in A1 (mp0, for crying out loud!!) inferno.
I realise that it is my fault for having the world's worst computer, and I can't complain about Battle.net's !@#$ servers, but if Blizzard could do something with lag issues, I would be eternally grateful. Having your character effectively incapacitated for fighting (apart from frozen, jailer, nightmare, etc.) for 10-12 seconds during a nasty mob fight (as was described above), is crazy.
Thank you for listening to my rant.