Virtual Function and ZeroMemory

What caused me to write this post is a BUG. Really i am not joking.. Everone know that there is a virtual table pointer is present at the beginning of the object memory . i am also know that.. But i did a mistake long ago . Following lines shows it...

class Base

{
public :
   virtual void Render()
   {
    }
};

class Derived: public Base

{
    // i have several data members here..
public :
    Derived()
    {
        // For easily initializing all of my data members to zero , i used ZeroMemory here
       ZeroMemory(this,sizeof(Derived));
       // Danger .. This also clear the virtual table pointer..
    }
    void Render()
   {
   }
};
So when i called it like
Derived *d = new Derived()
d->Render();

it crasheddd .... because of the ZeroMemory in the constructor set the vptr to Zero.