c언어 free()에 오류가 있는 것 같습니다..

#include <stdio.h>
#include <stdlib.h>
 
typedef int Element;
 
typedef struct tStackNode {
  Element data;  
  struct tStackNode *next;
} StackNode; 
 
typedef struct {
  int count;
  StackNode *top;
} Stack; 
 
Stack* CreateStack(int size)
{
  Stack *pStack = (Stack *)malloc(sizeof(Stack));
  if(pStack == NULL)
   return NULL;
 
  pStack->top = (StackNode *)malloc(size * sizeof(StackNode));
  if(pStack->top == NULL){
    free(pStack);
    return NULL;
  }
 
  pStack->top->next = (StackNode *)malloc(size * size * sizeof(StackNode));
 
 
  pStack->count = 0;
  pStack->top = NULL; 
  return pStack;
} 
 
 
void Push(Stack *pStack, Element item)
{
  StackNode *pNewNode = (StackNode *)malloc(sizeof(StackNode));
 
  if(pNewNode == NULL)
    return;
 
  pNewNode->data = item; 
  pNewNode->next = pStack->top; 
  pStack->top = pNewNode; 
 
  pStack->count++; 
  free(pNewNode);
  //pNewNode = NULL;
}
 
 
 
Element Pop(Stack *pStack)
{
  if(pStack->top == NULL)
    return 0;
  else {
 
    Element item = pStack->top->data;
    StackNode *pOldTop = (StackNode *)malloc(sizeof(StackNode));
    pOldTop = pStack->top;
    pStack->top = pOldTop->next;
    free(pOldTop);
    //pOldTop = NULL;
    pStack->count--;
    return item;
  }
}
 
 
void DestroyStack(Stack *pStack)
{
 
  if (pStack->top->next != NULL){
    free(pStack->top->next);
    pStack->top->next = NULL;
  }
 
  if(pStack->top != NULL)
  {
    free(pStack->top);
    pStack->top = NULL;
  }
 
  if(pStack != NULL) 
    free(pStack);
  return;
}
 
 
int main()
{
  int i = 0;
  int item = 0;
  Stack *pStack = CreateStack(100);
 
  printf("Input 10 numbers :"); 
  for(i = 0; i < 10; i++){
    item = 0;
    scanf("%d", &item);
    Push(pStack, item);
  }
 
  printf("Reversed :");
 
  while(pStack->count != -1){
    item = Pop(pStack);
    printf("%d ", item);
  }
 
  printf("\n");
 
 
  DestroyStack(pStack);
  pStack = NULL;
  return 0;
}