[Qt-interest] dll call function

[matteo]

We have a no-qt dll compiled with Borland/builder that call a function 
of a qt dll compiled in visual studio.
The problem is when I use QComboBox: if I open a widget with a combo, 
click on the combo, close the widget and reopen it, the system crash
(access violation at address 6702485f in module 'QtCodred4.dll'.
We call the function in way:

	int argc = 0;
	QApplication a(argc,NULL);
	GeneralDataWidget widgetGeneralDataWidget;
	widgetGeneralDataWidget.InternalEnter(); //my function
	widgetGeneralDataWidget.exec();

Suggestions?

Thanks
Teo