Wierd problem!

Hey all, I ran the code below , and it works just fine till the very end where dos says "hit any key to exit" (something like that).
THEN IT CRASHES MY COMPUTER!!!!!!!! I can't find the problem in it, though I suspect it's a pointer problem. Can someone please help me out! [the purpose of the program is to make the vector dot product, if some1 wants to see if the calculations are correct also, I would be pleased and grateful]
**THis program seems to only crash WIN ME in a blue screen way, other windows versions make the program disappear

#include <iostream>
#include <stdlib.h>
#include <math.h>
#include <fstream>
//ALLOCATE MEMORY
using namespace std;
//starting code for hwc
struct vector {int dimen;
double *x, mag;};
void loadvec(vector &vec) //use cin to read vector data
{
//ask user for dimension and vector elements
cout << "Enter vector dim: ";
cin >> vec.dimen;
cout<<"\nEnter Vector elements:";
double temp=0;
for(int i=0;i<vec.dimen;i++){
cin>>vec.x[i];
temp=(temp+(vec.x[i]*vec.x[i]));}
vec.mag=sqrt(temp);
//calculate the magnitude of the vector here too, sqrt of sum of sqrs
}
double dotprod(vector vec1, vector vec2)
{//right by other
double dp = 0;
for (int i =0; i < vec1.dimen; i++)
dp = dp + vec1.x[i]*vec2.x[i];
//calculate the dot product
return dp;
}
void vecprint(vector vec)
{
for (int i = 0; i < vec.dimen; i++)
cout << vec.x[i] << endl;
}
int main(int argc, char *argv[])
{vector vec1,vec2;
//ask user for 2 vectors using loadvec
loadvec(vec1);loadvec(vec2);
//print out dot product and magnitude of each vector
cout << "Input vectors are :\n";
vecprint(vec1);
cout <<"and \n";
vecprint(vec2);
cout << "Magnitude is: vec1:"<<vec1.mag<<" vec2:"<<vec2.mag<<endl;
cout<< "The dot product = " << dotprod(vec1, vec2) << endl;
//be sure to delete allocated memory
//delete......
//Also, write the results to a file given on the command line.
//ofstream outfile(agrv[1]);

system("PAUSE");
return 0;
}