heap corruption?

First of all, yes, this is a homework assignment. But as you'll see, I've already written the entire thing myself.
My program works how I want it to (excuse the poor coding i'm only a first year student) but everytime I end it, i get an error about a heap corruption. It triggers a breakpoint and says something like BLOCK_TYPE_IS_VALID. I've been trying to fix it for like 5 hours and have gotten nowhere. I looked at all my functions and they don't seem to be accessing out of bounds. I'd appreciate it if someone could spot where I'm going wrong and tell me how to fix it Here is all my code, nothing excluded.

myArray.h

#ifndef H_myArray
#define H_myArray

#include <iostream>

using namespace std;

class myArray
{
public:
	int& operator[] (int loc);
	const int& operator[] (int loc) const;
	myArray(int size = 20);
	myArray(int start = 0, int end = 20);
	~myArray();
	void showMenu();
	bool isEmpty() const;
	bool isFull() const;
	int getMaxSize() const;
	int getLength() const;
	int getStartLoc() const;
	void print() const;
	void sortAscending();
	void insertAt(const int& item, int position);
	int getChoice() const;
	void initialize();
	void search(const int& item) const;
private:
	int maxSize;
	int length;
	int startLocation;
	int *list;
	int choice;
};

#endif 

the implementation .cpp file for the class myArray

#include "myArray.h"
#include <iostream>
#include <cassert>
#include <string>

using namespace std;

//overload the [] operator to accomodate for start position
int& myArray::operator[] (int loc)
{
	assert(loc >= startLocation && loc < (maxSize + startLocation));
	loc = loc - startLocation;
	return list[loc];
}

//overload [] for constant arrays
const int& myArray::operator[] (int loc) const
{
	assert(loc >= startLocation && loc < (maxSize + startLocation));
	loc = loc - startLocation;
	return list[loc];
}

myArray::myArray(int size)
{
	startLocation = 0;
	maxSize = size;
	length = 0;
	if(maxSize == 0)
		list = NULL;
	else
	{
		list = new int[maxSize];
		initialize();
	}
}

myArray::myArray(int start, int end)
{
	startLocation = start;
	maxSize = (end - startLocation);
	length = 0;
	if(maxSize == 0)
		list = NULL;
	else
	{
		list = new int[maxSize];
		initialize();
	}
}

myArray::~myArray()
{
	delete [] list;
}

//display a menu and return the option selected
void myArray::showMenu()
{
	string input;
	bool valid = false;
	choice = 0;

	cout << "1: Insert an item into the list" << endl;
	cout << "2: Print the contents of the list" << endl;
	cout << "3: Search for an item" << endl;
	cout << "4: Sort the list in ascending order" << endl;
	cout << "5: Exit" << endl;
	cout << endl << ">> ";

	getline(cin, input);

	while(!valid)
	{
		if(input == "1")
		{
			choice = 1;
			valid = true;
		}
		else if(input == "2")
		{
			choice = 2;
			valid = true;
		}
		else if(input == "3")
		{
			choice = 3;
			valid = true;
		}
		else if(input == "4")
		{
			choice = 4;
			valid = true;
		}
		else if(input == "5")
		{
			choice = 5;
			valid = true;
		}
		else
		{
			cout << endl << "Invalid choice, please try again >> ";
			getline(cin, input);
		}
	}
	cout << string(50, '\n'); //clear the screen
}

//return true if the list is empty, false if not
bool myArray::isEmpty() const
{
	return (length == 0);
}

//return true if the list is full, false if not
bool myArray::isFull() const
{
	return (length == maxSize);
}

int myArray::getMaxSize() const
{
	return maxSize;
}

int myArray::getLength() const
{
	return length;
}

int myArray::getStartLoc() const
{
	return startLocation;
}

void myArray::print() const
{
	for(int i = startLocation; i < (maxSize + startLocation); i++)
	{
		cout << list[i] << " ";
	}
	cout << endl;
}

//sort the list in ascending order (lowest to highest) using bubble sort
void myArray::sortAscending()
{
	int temp;
	int iteration;
	int index;
	for(iteration = 1; iteration < maxSize; iteration++)
	{
		for(index = startLocation; index < (maxSize + startLocation) - iteration; index++)
		{
			if(list[index] > list[index + 1])
			{
				temp = list[index];
				list[index] = list[index + 1];
				list[index + 1] = temp;
			}
		}
	}
}

void myArray::insertAt(const int& item, int position)
{
	assert(position >= startLocation && position < (maxSize + startLocation));
	list[position] = item;
	length++;
}

int myArray::getChoice() const
{
	return choice;
}

void myArray::initialize()
{
	for(int i = startLocation; i < (maxSize + startLocation); i++)
		insertAt(0, i);
}

void myArray::search(const int& item) const
{
	bool found = false;
	int index;

	for(int i = startLocation; i < (maxSize + startLocation); i++)
	{
		if(list[i] == item)
		{
			found = true;
			index = i;
		}
	}
	if(found == false)
		cout << item << " was not found" << endl;
	else
		cout << item << " was found in the list " << endl;
}

main

/* Author: hehe
   Date: January 30, 2013
   Course: CS218a
   Assignment: Programming Exercise Week 4
   Purpose: Create and manipulate a dynamic array 
			with a custom starting index
*/
#include <iostream>
#include <string>
#include "myArray.h"

using namespace std;

int main()
{
	string input;
	while(input != "N" && input != "n" && input != "y" && input != "Y")
	{
		cout << "Create a list? [Y/N] >> ";
		getline(cin, input);
	}
	
	if(input != "N" && input != "n")
	{
		int start;
		int end;
		int choice = 0;

		cout << endl;
		cout << "Begin the array index starting at >> ";
		cin >> start;
		cout << "End the array at >> ";
		cin >> end;
		cout << string(50, '\n'); //clear the screen
		cin.ignore();
		//create the object with necessary parameters
		myArray arrayObj(start, end);

		//cycle the menu and options
		while(choice != 5)
		{
			arrayObj.showMenu();
	
			switch(arrayObj.getChoice())
			{
			case 1:
				int item;
				int pos;
				cout << "What number do you want to insert? >> ";
				cin >> item;
				cout << "At which index do you want to insert " << item << "? >> ";
				cin >> pos;
				cout << string(50, '\n');
				arrayObj.insertAt(item, pos);
				cout << item << " was inserted at index " << pos;
				cout << string(3, '\n');
				cin.ignore();
				break;
			case 2:
				cout << "Contents of the list:" << endl;
				arrayObj.print();
				cout << string(3, '\n');
				break;
			case 3:
				int num;
				cout << "Which number do you want to search for? >> ";
				cin >> num;
				cout << string(50, '\n');
				arrayObj.search(num);
				cout << string(3, '\n');
				cin.ignore();
				break;
			case 4:
				arrayObj.sortAscending();
				cout << "List sorted" << endl;
				cout << string(3, '\n');
				break;
			case 5:
				cout << "Have a nice day :)/>" << endl;
				break;
			}//end switch
			choice = arrayObj.getChoice();
		}//end while
	}//end if

	cout << endl;
	system("pause");
	return 0;
}