使用删除时随机崩溃

我正试图用C++和Allegro 4.2.3编写我的第一个简单游戏，但当我更改游戏状态时，有时会出现崩溃。当一个状态启动时，它会使用"new"运算符创建它，然后在切换到下一个状态之前使用"delete"。不过，我不确定我是否完全理解使用new和delete运算符！以下是代码选择：

enum    //Game state
{
    TITLE_SCREEN, CUTSCENE_1
};
int main(void)
{
    const int screenwidth = 800;
    const int screenheight = 600;
    bool quit = false;
    int state = TITLE_SCREEN;
    int oldstate = -1;
    int oldoldstate;
    init(screenwidth, screenheight);
    install_int(counter, (1000/FPS));
    TitleState *Title;
    Cutscene *Scene1;
    srand (time(NULL));
    while (!quit) 
    {
        while(tick == 0)
        {
            rest(1);
        }
        while(tick > 0)
        {
            oldoldstate = oldstate;
            oldstate = state;
            switch(state)
            {
            case TITLE_SCREEN:
                //If the last state is different to this one, create the state
                if(oldoldstate != TITLE_SCREEN)
                {
                    Title = new TitleState();
                }
                //Run the program in the state
                Title->Play();
                //Check the state to see if it has changed
                state = Title->CheckState();
                //If the state has changed, delete the current state
                if(oldstate != state)
                {
                    delete Title;
                }
                break;
            case CUTSCENE_1:
                if(oldoldstate != CUTSCENE_1)
                {
                    Scene1 = new Cutscene();  //SOMETIMES CRASHES BEFORE HERE
                }
                Scene1->Play();
                state = Scene1->CheckState();
                if(oldstate != state)
                {
                    delete Scene1;
                }
                break;
            case EXIT:
                quit = true;
                break;
            default:
                allegro_message("Game state not found!");
                exit(-1);
            }
            int oldtick = tick;
            tick--;
            if(oldtick <= tick)
                break;
        }
    }
    deinit();
    return 0;
}

当程序崩溃时，VS2010打开线程.c来显示错误所在：

static void _callthreadstart(void)
{
    _ptiddata ptd;           /* pointer to thread's _tiddata struct */
    /* must always exist at this point */
    ptd = _getptd();
    /*
     * Guard call to user code with a _try - _except statement to
     * implement runtime errors and signal support
     */
    __try
    {
        ( (void(__CLRCALL_OR_CDECL *)(void *))(((_ptiddata)ptd)->_initaddr) )
            ( ((_ptiddata)ptd)->_initarg );    //ERROR HERE (Next statement to be executed)
        _endthread();
    }
__except ( _XcptFilter(GetExceptionCode(), GetExceptionInformation()) )
    {
            /*
                * Should never reach here
                */
            _exit( GetExceptionCode() );
    } /* end of _try - _except */
}

如果有任何帮助，我将不胜感激，因为我根本不确定问题出在哪里。