How hot does the device get under your test conditions? Are you following the recommendations for the thermal pad on the chip? If it is in a circuit, I would have to doubt ESD damage. So that leaves excess power supply levels, extreme voltage spikes on an input or output (echo-ing Ron's worry about any inductive loads on the outputs), or over temperature.
When you say that it dies, is it completely dead? No communication through the I2C bus at all? That might help narrow down the failure cause.
-Jim