Galileo AnalogRead() not accurate in case of Low Current.

I've attached a few graphs of voltage readings from the Intel Galileo, via the following code:

int Pin = A5;    // select the input pin for the potentiometer

void setup() {

  Serial.begin(9600);

}

void loop() {

  analogReadResolution(10);        // 5V => 1024

  Serial.println(analogRead(Pin));

  delay(100);       

}

I'm running a dead simple circuit: just 5 equal resistance resistors in series, connected to GND and 5V.

The graph contains the voltage readings between each resistor (that is, 0V, 1V, 2V, 3V, 4V, 5V, if Ohm's law holds).

    For Line 1, each of the resistors had 1kΩ resistance.

    For Line 2, each of the resistors had 10kΩ resistance.

    For Line 3, each of the resistors had 470kΩ resistance.

    For Line 4, each of the resistors had 1MΩ resistance.

It turns out the Galileo gets abnormally low readings if the resistors have high enough resistance, but the RedBoard from sparkfun and the Arduino give the correct readings, regardless of the total resistance. Does anyone else have this problem?