OpenCV console application - c++

Question

I got an example of making contours around what it sees in a bitmap picture, and it works great!
But, the code is going to be part of a bigger project using leap motion and I need it to run in a console and just give me the values. I don't need any windows to be opened.
So when I am running the following code, I get _pFirstBlock == pHead. I searched for the error and it seemed to be that my DLL's are not in Multi-threaded Debug DLL (/MDd), but they are. I know this because if I delete everything in main(), the application works fine. If I run the application as usual, I get the error at the end of main() - when releasing memory. I put all my code from main() in an empty scope just to validate this, and it crashes with the same error at the end of the scope.
So it clearly has something to do with releasing memory.
What would it be?
Using OpenCV 2413
Full code:
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
using namespace cv;
using namespace std;
Mat src; Mat src_gray;
int thresh = 20;
RNG rng(12345);
int main(int, char** argv)
{
{
src = imread(argv[1], 1);
cvtColor(src, src_gray, COLOR_BGR2GRAY);
blur(src_gray, src_gray, Size(3, 3));
cout << endl;
Mat threshold_output;
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
threshold(src_gray, threshold_output, thresh, 255, THRESH_BINARY);
findContours(threshold_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));
vector<vector<Point> > contours_poly(contours.size());
vector<Point2f>center(contours.size());
vector<float>radius(contours.size());
for (size_t i = 0; i < contours.size(); i++)
{
approxPolyDP(Mat(contours[i]), contours_poly[i], 3, true);
minEnclosingCircle(contours_poly[i], center[i], radius[i]);
}
cout << "Found " << contours.size() << " contours. " << endl;
Mat drawing = Mat::zeros(threshold_output.size(), CV_8UC3);
for (size_t i = 0; i < contours.size(); i++)
{
Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
circle(drawing, center[i], (int)radius[i], color, 2, 8, 0);
cout << "Found one at: (" << center[i].x << ", " << center[i].y << ") radius = " << radius[i] << endl;
}
drawing.release();
threshold_output.release();
src_gray.release();
src.release();
} //////////// CRASHES
return(0);
}