Now that I've moved from using the Arduino Uno to the Arduino Nano, i've come across a problem. The first line, everytime, that comes through to the Pi through the serial connection is this x00. Which is then having a domino effect, as the splicing and numeric property of the list that is generated for the sensor readings from this input cant function, and so the GUI fails. Below shows this output, using the simple serial test code:

I don't know why this is?? If anyone can shine any light on it?? 

Is it the move from the Uno to the Nano?

This seems to be a fault with the Raspberry Pi side of things, as when I connect the Arduino Nano and FSR Sensors into to the computer and run the serial monitor in the Arduino IDE, its transmitting just the numbers and comma's as instructed: