analogue pin 0 problem

I have got a simple line sensor which i will eventually use to make a robot that will follow a line. When i plug it into analog pin 1,2,3,4, or 5 the values are all within the same range apart from when it is plugged into pin 0. I don't know why, is it some kind of setting or something that i am doing wrong?? Thank you for your help!!

Since writing i have noticed that the pin is slow to react to change it give loads of intermediary values before giving the current reading. Can it be changed?