Kicked from the game for "performing too many actions too fast"

I was doing "The Phaaryl Megalith" map and I got to the final boss encounter after killing the rest of the bosses and then I was booted out of the game and given this message: "You have been kicked for performing too many actions too fast."
Any ideas as to why this happened apart from the obvious? My build is good but it still shouldn't get me kicked from the game ?