Empty ByteBuffer size?

I made a custom-made text box for inputs, which works like entering text into a forum field. I can backspace, delete, type, etc... However, there's an issue when I call .setText(String) of my custom-made text field, and try to "delete" any of the letters already there. For the one field, I put "username" for obvious reasons.

If I type in a letter before erasing, it works fine, but if I erase what characters "exist", or rather, the ones that aren't empty spaces, then it crashes.

Anywho, down the line, this code gives me the following error from my LetterList class:

letterTex = TextureLoader.getTexture("PNG",letterFile,true);
(letterTex is a Texture object)



Exception in thread "main" java.lang.IllegalArgumentException: Buffer size <= 0

	at java.io.BufferedInputStream.<init>(BufferedInputSt  ream.java:193)

	at org.newdawn.slick.opengl.CompositeImageData.loadIm  age(CompositeImageData.java:53)

	at org.newdawn.slick.opengl.CompositeImageData.loadIm  age(CompositeImageData.java:43)

	at org.newdawn.slick.opengl.InternalTextureLoader.get  Texture(InternalTextureLoader.java:277)

	at org.newdawn.slick.opengl.InternalTextureLoader.get  Texture(InternalTextureLoader.java:231)

	at org.newdawn.slick.opengl.InternalTextureLoader.get  Texture(InternalTextureLoader.java:184)

	at org.newdawn.slick.opengl.TextureLoader.getTexture(  TextureLoader.java:64)

	at org.newdawn.slick.opengl.TextureLoader.getTexture(  TextureLoader.java:37)

	at LetterList.letterSearch(LetterList.java:285)

	at GameInputBox.drawTypedWord(GameInputBox.java:472)

	at GameInputBox.draw(GameInputBox.java:226)

	at IntroWindow.<init>(IntroWindow.java:221)

	at MainControl.setMainState(MainControl.java:40)

	at ConnectionTester.<init>(ConnectionTester.java:107)

	at MainControl.setMainState(MainControl.java:31)

	at MainControl.<init>(MainControl.java:13)

	at MainControl.main(MainControl.java:17)

	at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ  e Method)

	at sun.reflect.NativeMethodAccessorImpl.invoke(Native  MethodAccessorImpl.java:57)

	at sun.reflect.DelegatingMethodAccessorImpl.invoke(De  legatingMethodAccessorImpl.java:43)

	at java.lang.reflect.Method.invoke(Method.java:601)

	at com.intellij.rt.execution.application.AppMain.main  (AppMain.java:120)

I've been digging and digging, and nothing seems off about my code. So I don't get it.

Here's the setText(String) method if it helps any:

Code java:

public void setText(String text) {
        if (text.length() > maxLetters) {
            try {
                throw new TextLengthException(maxLetters);
            } catch (TextLengthException e) {
                e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
                System.exit(-1);
            }   // try - catch TextLengthException
        } else if (text.length() < maxLetters) {
            // save entry size
            entryLength = text.length();
 
            // create extra letters
            addExtras = new char[maxLetters-text.length()-1];
            // append letters to text
            for (int i = 0; i < addExtras.length; ++i) {
                addExtras[i] = '¶';
            }   // for loop
 
            // add to text
            text = text + String.valueOf(addExtras);
        }   // else - if
        else
            entryLength = text.length();
 
        // finally save to array
        saveEntry = text.toCharArray();
        storeText();    // stores the created text to showText for visual display
    }   // setText(String)

EDIT: Apparently this bug happens when I run the program on my desktop Windows 7 Home Premium x86 (64-bit) OS, but when I run it on my laptop (has XP and 7 on 2 partitions), it works perfectly normal.

This was originally programmed on my laptop, so I never noticed the issue until recently when testing 2 programs on the Desktop.