Analog ports disturbed

A0 is the potentiometer
A1 is connected to a couple of resistor (voltage divider from 12v to 5v)
A2 is connected to a lm35 termometer

in recent test i've noticed that when A1 is to 0 (potentiometer completely closed) the reading of the other two ports is perfect and stable. When i activate the potentiometer it goes all crazy