Random number generator sometimes fails to start in Eclipse - eclipse

Question

I have written some code that produces an object which returns a unique random number when queried. However, every once in about 6 or 7 runs the program fails to start, and there seems to be no apparent reason for this. Also, my memory seems to drop over time (using a vector in the class). Any ideas?
/*
* Urn.h
*
* Created on: Jan 17, 2014
* Author: edwinrietmeijer
*/
#ifndef URN_H_
#define URN_H_
#include <cstdlib>
#include <vector>
#include <iostream>
class Urn {
private:
int highRand;
int loRand;
int numsTotal;
int numsLeft;
std::vector<int>numsAvailable;
public:
Urn();
int getRand();
int getSize();
void reset();
virtual ~Urn();
};
#endif /* URN_H_ */
/*
* Urn.cpp
*
* Created on: Jan 17, 2014
* Author: edwinrietmeijer
*/
#include "Urn.h"
using namespace std;
Urn::Urn() : highRand( 9 ), loRand( 0 ) {
vector<int>::iterator pos;
int newRandom;
numsTotal = highRand - loRand;
bool newRandomExists = false;
while ( numsAvailable.size() < numsTotal + 1 )
{
do {
newRandomExists = false;
newRandom = ( rand() % ( numsTotal + 1 ) ) + loRand;
for ( pos = numsAvailable.begin(); pos != numsAvailable.end(); pos++ ) {
// cout << *pos << " ";
if ( *pos == newRandom ) {
newRandomExists = true;
}
}
// cout << " Random -> " << newRandom << " " << newRandomExists << endl;
} while ( newRandomExists == true );
newRandomExists = false;
numsAvailable.push_back( newRandom );
}
cout << endl;
// List the list
for (pos = numsAvailable.begin(); pos != numsAvailable.end(); pos++ ) {
// cout << *pos << " ";
}
// cout << endl;
// TODO Auto-generated constructor stub
}
int Urn::getRand() {
vector<int>::iterator pos = numsAvailable.begin();
int numToReturn = numsAvailable.back( );
numsAvailable.erase( pos );
return numToReturn;
}
int Urn::getSize() {
return numsAvailable.size();
}
void Urn::reset() {
}
Urn::~Urn() {
// TODO Auto-generated destructor stub
}
//============================================================================
// Name : UniqueRand.cpp
// Author : Edwin Rietmeijer
// Version :
// Copyright : This code is owned by Edwin Rietmeijer as of 2014
// Description : Hello World in C++, Ansi-style
//============================================================================
#include <iostream>
#include <string>
#include "Urn.h"
using namespace std;
int main() {
cout << "Seeding..." << endl;
srand( time( NULL ) );
cout << "Getting object..." << endl;
Urn * urnObject = new Urn;
cout << urnObject -> getRand();
return 0;
}