Text error with LWJGL and Slick2D

I've been attempting to build a small program with the LWJGL just to go teach myself a bit of graphics, when I try to overlay text onto a 2D scene i'm drawing (this being a box that continuously bounces off all the sides of the window) the text becomes blurred and the box flickers repeatedly - https://i.stack.imgur.com/OATmd.jpg Stranger still, if I copy the font.drawString line but have it display a single word instead of the co-ords it doesn't flicker at all but is still blurry - https://i.stack.imgur.com/vnIK6.jpg.

Would anyone be able to help me with why this is happening and how I would fix it? I'm quite proficient in Java but this is the first time i've attempted anything graphics orientated.

import java.nio.FloatBuffer;
import java.text.DecimalFormat;

import org.lwjgl.LWJGLException;
import org.lwjgl.Sys;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;

import org.newdawn.slick.SlickException;
import org.newdawn.slick.UnicodeFont;
import org.newdawn.slick.font.effects.ColorEffect;

import org.lwjgl.BufferUtils;

import static org.lwjgl.opengl.GL11.*;


public class TimerDemo
{
//time in ms since the last frame was rendered
private static long lastFrame;

//current time in ms
private static long getTime()
{
    return (Sys.getTime() * 1000) / Sys.getTimerResolution();
}

//gets the difference between the current time and lastFrame, then updates lastFrame
private static double getDelta()
{
    long currentTime = getTime();
    double delta = (double) (currentTime - lastFrame);
    lastFrame = getTime();
    return delta;
}


private static UnicodeFont font;
private static void setUpFonts()
{
    java.awt.Font awtFont = new java.awt.Font("Arial", java.awt.Font.PLAIN, 12);
    font = new UnicodeFont(awtFont);
    font.getEffects().add(new ColorEffect(java.awt.Color.white));
    font.addAsciiGlyphs();

    try
    {
      font.loadGlyphs();
    } 
    catch (SlickException e)
    {
        e.printStackTrace();
    }
}

public static void main(String[] args)
{
    try
    {
        Display.setDisplayMode(new DisplayMode(680, 480));
        Display.setTitle("Timer Demo");
        Display.create();
    }
    catch (LWJGLException e)
    {
        e.printStackTrace();
        Display.destroy();
        System.exit(1);
    }

    setUpFonts();

    //position
    int x = 100;
    int y = 100;

    //velocity
    int dx = 1;
    int dy = 1;

    //ensure lastframe is updated
    lastFrame = getTime();

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0, 680, 480, 0, 1, -1);
    glMatrixMode(GL_MODELVIEW);


    while (!Display.isCloseRequested())
    {
        // Render

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glLoadIdentity();

        //change in position
        double delta = getDelta();

        if(x + 30 >= 680)
            dx = -1;
        else if (x <= 0)
            dx = 1;

        if(y + 30 >= 480)
            dy = -1;
        else if (y <= 0)
            dy = 1;

        x += delta * dx * 0.1;
        y += delta * dy * 0.1;

        glRecti(x, y, x + 30, y + 30);

        font.drawString(100, 10, "x is " + x + " y is " + y);


        Display.update();
        Display.sync(60);
        }

    Display.destroy();
    System.exit(0);
}
}

Copyright Notice：Content Author:「Pastadin」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/19011174/text-error-with-lwjgl-and-slick2d