Arduino Due libraries (official and 3rd party)

I installed the new release of Arduino IDE 1.5.5. but I have some problem.

  1. in I2C comunication, infact if I try to use the MLX90914 sensor I can't read value.

  2. I have a sketch that read from analog input the value of accelerometer. after I installed the IDE 1.5.5 I can't read correctly the value.

somebody can help me?