I can't seem to figure out why there is a segmentation fault in my copy constructor.

Set::Set()
{
   Num = 0;
   Head = new (nothrow) Node;
   Head->Succ = NULL;
}
Set::Set( const Set & A)
{
   Node * Temp = A.Head->Succ;
   while ((Temp) )
   {
      insert(Temp->Item);
      Temp = Temp->Succ;
   }
}

The problem is the constructor with the parameter. It also needs to initialize instance variables because the constructor with no parameters does not get called.