Originally Posted by Rage
Haven't watched IM2 in a while... but I thought the problem with the arc reactor was that the powersource was too powerful for the rest of the unit and eventually burnt through itself and that was causing the poisoning in Stark's system. Stark created Vibranium to case the arc in, so it would not be able to burn itself/and the system out... what he created was a way to contain the power... not the power source itself.
I haven't seen IM2 in a long while, but I do remember in IM, when Pepper is helping to remove the AR from his chest, she's grossed out by the pus, which Tony corrects her that it's a discharge from the device. I think the discharge was what was poisoning him.