Found this on Blizzard D3 General forums:
"So, this has happened to me twice now. Basically, I was fighting some elites and my health dropped down to zero but I didnt die (my screen edges went red and everything). I was so convinced I was dead that I just kind of sat there waiting for the respawn button to come up.
Oddly enough it didn't yet mobs were still attacking me, so I tried to attack back and it worked. After killing the elites I decided to go and try and commit suicide elsewhere, sure enough my health would drop down to zero (and until I used a potion I couldn't move or attack) but I didn't die.
Obviously this made the rest of the farm rather amusing
None of my friends have experienced this but they were in a game with me when it happened, so they believe it happens after seeing it themselves.
Anyone else had this truly awesome bug? I'd love to know how to recreate it lol."
Could be a troll post but a few other users commented that they experienced the same recently.
Sorry if this is useless info... this is my first post. I only thought it was interesting because he said he was able to keep killing mobs, which sounds like he still has communication with the server.