二进制搜索树分段错误

我已经为此挣扎了一段时间。我有一个BST，它的设计目的是在插入时遇到重复时递增计数器。这完全符合设计。

树将丢弃此元素，而树保持不变。但是，我想删除树中的原始元素，这样第三次插入重复元素不会增加计数器。当我运行程序时，我会出现segfault。请参阅下面的代码。GDB说segfault发生在InsertInto（）方法中，ValGrind抱怨我找不到一堆内存泄漏。

任何帮助都将不胜感激。

struct BSTreeNode
{
    int mData;
    BSTreeNode *mLeft, *mRight;
    BSTreeNode(int i)
    {
        mData = i;
        mLeft = NULL;
        mRight = NULL;
    }
    ~BSTreeNode()
    {
        delete mLeft;
        delete mRight;
    }
};
class BSTree {
    private:
        BSTreeNode * mRoot;
        bool mWithDeletion;
    public:
        int mDupCounter;
        BSTree():mRoot(NULL),mDupCounter(0),mWithDeletion(false){}
        BSTree(bool _withDelete):mRoot(NULL),mDupCounter(0),mWithDeletion(_withDelete){}
        ~BSTree()
        {
            delete mRoot;
        }
        BSTreeNode * FindSmallest(BSTreeNode *& _node)
        {
            if (!_node->mLeft)
                return _node;
            else
                return FindSmallest(_node->mLeft);      
        }
        void DeleteNode(BSTreeNode *& _node)
        {
            if (!_node->mLeft && !_node->mRight) // no subtrees
            {
                delete _node;
                _node = NULL;
            }
            else if (_node->mLeft && !(_node->mRight)) // only left subtree
            {
                _node = _node->mLeft;
            }
            else if (_node->mRight && !(_node->mLeft)) // only right subtree
            {
                _node = _node->mRight;
            }
            else // both subtrees exist.
            {
                BSTreeNode * temp = FindSmallest(_node->mRight);
                _node->mData = temp->mData;                 
                DeleteNode(temp);
            }
        }
        void InsertInto(BSTreeNode *& _node, int _valueToInsert)
        {   
            if (!_node)
            {
                _node = new BSTreeNode(_valueToInsert);
            }
            else if (_valueToInsert < _node->mData)
            {
                InsertInto(_node->mLeft, _valueToInsert);           
            }
            else if (_valueToInsert > _node->mData)
            {
                InsertInto(_node->mRight, _valueToInsert);
            }
            else
            {
                cout << "DUPLICATE FOUND!" << endl;
                mDupCounter++;              
                // delete the node already in the tree if we must
                if (mWithDeletion)
                    DeleteNode(_node);              
            }
            cout << endl;
        }
        void InsertIntoRoot(int _valueToInsert)
        {
            InsertInto(mRoot, _valueToInsert);
        }
};