Exception when calling std::list::push_back

I have a class TextureManager class which has a std::list of pointers to Ressource

    struct Ressource
    {
        sf::Image img;
        std::string path;
    };

I get this error:

std::_List_alloc<std::_List_base_types<ASC::TextureManager::Ressource *,std::allocator<ASC::TextureManager::Ressource *> > >::_Myhead(...) returned 0x4.

methods:

    const sf::Image& TextureManager::load(std::string dPath)
    {
        Ressource * res = new Ressource;
        res->img.loadFromFile(dPath);
        res->path = dPath;

        data.push_front(res);

        return res->img;
    }   

    const sf::Image& TextureManager::get(std::string dPath)
    {
        return load(dPath);
    }

the TextureManager is a member of RessourceHandler which has the following getter method:

const sf::Image& RessourceHandler::getTexture(std::string path)
{
    return tManager.get(path);
}

That method gets called by different objects which have a pointer to an instance of the RessourceHandler. Thats when the exception gets thrown.

it works all fine if i delete the line where i push_back the Ressource into the list at TextureManager::load()

it also works fine when i call TextureManager::load() from the RessourceHandler's Constructor. Even without deleting the push_back.

I can't figure out why that happens. has anyone an idea?