Why would an IndexArrayOutOfBounds occur when the code hasn't been altered?

Question

I'm asking this because I've been testing an algorithm I made, and now I'm getting ArrayIndexOutofBounds exception.
I didn't edit or alter the code in any way.

Answer 1

Seriously it was working fine until a few moments ago.
int[] array = read(new File("C:/countingSort.txt");
int sorted[] = new int[array.length];
          long start = System.currentTimeMillis(); //Starts the timer
          int k = 0;
               for(int i = 0; i < array.length; i++)
                    if(array[i] > k)
                         k = array;
countingSort(array, sorted, array.length); //Runs the countingSort method
long end = System.currentTimeMillis() - start; //Ends the timer
private static void countingSort(int input[], int sorted[], int k)
     int i, j;
     int count[] = new int[k];
          for (int m = 0; m < 1000; m++)
               for (i = 1; i < k; i++)
                    count[i] = 0;
               for (j = 1; j < input.length; j++)
                    count[input[j]] = count[input[j]] + 1;
               for (i = 2; i < k; i++)
                    count[i] = count[i] + count[i - 1];
               for (j = 1; j < input.length; j++)
                    sorted[count[input[j]]] = input[j];
                    count[input[j]] = count[input[j]] - 1;
The output says...
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 39
at CountingSort.countingSort<CountingSort.java:66>
at CountingSort.main<CountingSort.java:26>
I did not alter the code in any way. I was just testing it then this occurred. Any help would be brilliant because I have no idea.
Thank you.