mex out of memory

Hello, I know there are already several question about out of memory in combination with mex. When i call the mex function the first time no problem, after that out of memory. Looks like a memory leak. But i don't know why. Maybe I can get some help here? In Matlab I just call the mex-Function in the command window. Following I will post the code snippet where it accurs.

#include "urg_sensor.h"
#include "urg_utils.h"
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
#include "mex.h"
#pragma comment(lib,"wsock32.lib")

 int getDistance(long* data);
void setReturnVector(mxArray *plhs[], int index, long* vector);

 static int initialized = 0;
static urg_t *urg;
void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
  {
...
          long *data = NULL;
          int n;
          data = (long *)mxMalloc(urg_max_data_size(urg) * sizeof(data[0]));
          n = getDistance(data);
          setReturnVector(plhs, 0, data);
          //mxFree(data); 
}

 int getDistance(long *data){
        long time_stamp;
        int n;

        mexPrintf("LaserScanner: Measuring...\n");
        n = urg_get_distance(urg, data, &time_stamp);
        return n;
}

 void setReturnVector(mxArray *plhs[], int index, long* vector){
    plhs[index] = mxCreateNumericMatrix(0,0,mxINT32_CLASS, mxREAL);
    mxSetData(plhs[index], vector);
    mxSetM(plhs[index], (int) urg_max_data_size(urg)/2);
    mxSetN(plhs[index], 1);
}

[Geoff Hayes]

Ronron - you've commented out mxFree. Why after allocating memory using mxMalloc?

[James Tursa]

@Geoff: The mxFree needs to be commented out because the data address is being attached to an mxArray data area via the setRetrunVector call and the mxSetData(plhs[index],vector) line. Having mxFree(data) execute would invalidate plhs[0] and likely crash MATLAB.

@Ronron: Is your posted code the only code that allocates any memory? Do you actually get an "out of memory" error message on the screen?