GTk::VBox derived class question

[Al-Burak]

I know that this is not a C++ question, but in the hope that some other
programmer with GTKmm programming experience would come to this
newsgroup, read my message and give me a hand on this issue I am
posting the question here.I know that there is a mailing list for
GTKmm, however, the list is very slow; to a point where one feel lucky
to get a reply, what a shame.
I am trying to write a class that derives from Gtk::VBox called
Contacts; the idea is to pack every widget necessary to display and
retrieve data from the user using a one class. This class will be
passed to a Gtk::Notebook::append_page().
The class compiles just fine, but at the point where I add the
Gtk::HBox object to the Gtk::VBox derived class the program
craches/segmentation fault.

Could someone please tell me what I am doing wrong?

Here is the example:
==========
WinXP
MinGW-GCC

class Contacts : virtual public Gtk::VBox{
protected:
   Gtk::HBox hbox1;
   Gtk::HBox hbox2;

public:
       Contacts();
       virtual ~Contacts();
}; //class
jme::Contacts::Contacts(){
   this->pack_start(hbox1); //Segmentation Fault
}
==============

TIA