Failure when testing Java HashMap implementation: Works for ~99% of values only

I wrote a HashMap implementation for simple integer-string key-values in Java. In attempting to test it, I wrote some test code, and saw that for between 0-4 of the values (out of a sample of 5000) each time, the test was failing. So I then switched my HashMap to the Java default implementation, and noticed that my tests were failing the obviously correct implementation. So, I have been hung up for the past couple hours trying to figure out why my test is failing. Is there something I am missing? (Well, obviously there is...)

Here is my code:

package HashMapOther;

import java.math.BigInteger;
import java.security.SecureRandom;
import java.util.HashMap;

public class StudentStore {
    private static SecureRandom random = new SecureRandom();
    static HashMap<Integer, String> map;
    static String[] studentNames;
    static int[] keys;
    static int magicNumber =5000; //still fails no matter size

    public static void main(String[] args){
        long startTime = System.currentTimeMillis();
        start();
        test();
        long endTime = System.currentTimeMillis();
        System.out.println("TIME: " + (endTime - startTime) + " ms");
    }

    public static void start(){
        studentNames = getStudents(); //random strings
        keys = getKeys(); //random integers
        map = new HashMap<Integer, String>(magicNumber, (float) 0.7);
        for(int i=0; i< magicNumber; i++){
            map.put(keys[i],studentNames[i]);
        }
    }

    public static int[] getKeys(){ //random integers
        int[] a = new int[magicNumber];
        for(int k=0; k< magicNumber; k++){
            a[k] = (int) (Math.random()*10000000+1);
        }
        return a;
    }

    public static String[] getStudents(){ //random strings
        String[] temp = new String[magicNumber];
        for(int i=0; i<magicNumber; i++){
            temp[i] = randomString();
        }
        return temp;
    }

    public static String randomString(){ //random string
         return new BigInteger(130, random).toString(32);
    }

    public static void test(){ //test code
        boolean passed = true;
        for(int i=0; i<magicNumber; i++){
            if(!studentNames[i].equals(map.get(keys[i]))){
                System.out.println("FAILURE: "+studentNames[i] + " " + map.get(keys[i]));
                passed = false;
            }
        }
        System.out.println("RESULT: " + passed);
    }
}

And here is sample output:

FAILURE: vq0cpihdsr4vfru6126suufvp4 3dq4shra6dps49psehqjuof4ib
FAILURE: lo2t73n1upqk6cmirdpui29ndt r6accv6ja5pkv723c5g0fe0d1q
RESULT: false
TIME: 94 ms

or, in another run:

RESULT: true
TIME: 104 ms

and, another:

FAILURE: c7848b9rejbtguj2d70llotvpu od7r0fjdphvdli6mgonbictg4d
FAILURE: 4ouk2cj9ipoo4hjrco8vd6p7e kt0u925jdn102cjul96thsfhcm
FAILURE: 2spd0u9lp7531hm09rqu8oncvm scrui9hl7tr0aq85at13oekgf7
RESULT: false
TIME: 99 ms