OpenCv error when initializing camera with VisualStudio C++ 2010

I'm new to opencv programming, so maybe my question will be very stupid. But i have such problem, i took one sample code, which should enable laptop webcamera to show image in desktop.

#include <opencv\cv.h> 
#include <opencv\highgui.h> 

using namespace cv;

int main()
{
Mat image;   //create Matrix to store image
VideoCapture cap;
cap.open(0);     // initialize capture
namedWindow("window", CV_WINDOW_AUTOSIZE);  // create window to show image

while(1)
{
cap>>image;  // copy webcam stream to image
imshow("window", image);   // print image to screen
waitKey(33);      // delay 33ms
}
return 0;
}

But when i'm trying to debug it i get an error message.

Unhandled exception at 0x5a16ebe6 in myNewOpenCV.exe: 0xC0000005: Access violation reading location 0x00000018.

But if i put breakpints on

cap>>image;
 imshow("window", image);   // print image to screen`

and after debuging im taking it off everything work correctly. Maybe someone can help to find a problem. Thanks.