Java Stack Overflow when reading Object

I'm trying to load an object into Java that I had saved from a program I had made.

When loading it in, Java threw a Stack Overflow Error.

The object I'm loading in had about a thousand entry object ArrayList inside of it, and in total ended up being around 128 Kb when exported.

I understand that a Stack Overflow happens when I make too many recursive calls, but I don't understand how loading in one array list of objects can cause this to happen?

I'm a self-taught programmer, so any insight would be appreciated that could help me better understand the problem.

Here's my code for the class I'm trying to load (Memboric)

    public class Memboric implements Serializable{

    /**
     *
     * The Memboric Core stores the various databases the AI needs to function.
     *
     * @author Brayden McKinney
     * @date 5/14/2013
     */

    private static final long serialVersionUID = 4477889114653605232L;

    ArrayList<String> knownWords = new ArrayList<String>();
    HashMap<String, Word> thesaurus = new HashMap<String, Word>();
    ArrayList<ConversationLog> conversations = new ArrayList<ConversationLog>();

    File location = null;

    public static Memboric load(File location){
            Memboric memboric;

            try{
                    FileInputStream file = new FileInputStream(location);
                    ObjectInputStream oo = new ObjectInputStream(file);
                    memboric = (Memboric) oo.readObject();
                    oo.close();
                    System.out.println("Memboric Core loaded and mounted successfully.");
                    return memboric;
            }catch(FileNotFoundException fn){
                    System.err.println("Failed to load Memboric Core.");
            }catch(InvalidClassException ic){
                    System.err.println("Memboric Core is incompatible.");
            }catch(Exception e){
                    e.printStackTrace();
            }

            System.err.println("Creating new Memboric Core.");
            return new Memboric();
    }

    public boolean save(File location){
            this.location = location;

            try{
                    FileOutputStream file = new FileOutputStream(location);
                    ObjectOutputStream oo = new ObjectOutputStream(file);
                    oo.writeObject(this);
                    oo.close();
                    System.out.println("Memboric Core saved successfully.");
                    return true;
            }catch(FileNotFoundException ex){
                    try{
                            if (location.createNewFile()) save(location);
                    }catch(IOException exx){
                            exx.printStackTrace();
                    }
            }catch(Exception e){
                    e.printStackTrace();
            }

            return false;
    }

And it's sister class (Word) that it contains:

    public class Word implements Serializable{

    private static final long serialVersionUID = 790247641945230263L;

    private String word;

    ArrayList<String> definitions = new ArrayList<String>();
    ArrayList<Word> synonyms = new ArrayList<Word>();
    ArrayList<String> tags = new ArrayList<String>();
    HashSet<String> links = new HashSet<String>();
    }

The error itself can be seen here (it's rather large): http://pastebin.com/46bFZYVp

Also, the code above is cut down to save space (I removed the non-related parts) but the full classes can be seen here:

http://pastebin.com/tptmZ2LC http://pastebin.com/3ickseFL