Multiple Inheritance Problem

[Rigel]

There was a bug that stumped me for a while and I'd like to know the exact reason why this is happening.
I'm going to simplify the problem here.

class Base1 - Concrete class
{
virtual void DoSomething1(){}
}
 
class Base2 - Abstract class
{
virtual void DoSomething2()=0;
}
 
class Derived : Base1, Base2
{
void DoSomething1(){}
void DoSomething2(){}
}

When I create a new instance of Derived and call DoSomething2(), the function that gets invoked is DoSomething1()

However, here is what the root cause appears to be.

EDIT: Example was slightly off we are casting back to Base2.

 
Derived *d = new Derived();
DWORD dPtr = (DWORD)d;
Base2 *b2 = (Base2*) dPtr;
b2->DoSomething2(); //DoSomething1() is called

How come casting to a DWORD and then casting back to Derived* screws things up?