I discovered a bug wery weird when running a simple program written with Qt 5.5 .
The following code:

int main(int argc, char **argv)
{
QApplication myapp(argc, argv);

	QFileSystemModel *model = new QFileSystemModel;
	QModelIndex idx = model->setRootPath("C:/");

	QTreeView *tv = new QTreeView;
	tv->resize(640, 480);
	tv->setModel(model);
	tv->setRootIndex(idx);
	tv->show();
	return myapp.exec();
}

It crashes when I execute it in release 64 Bits on a laptop with Windows 8.1 Pro. This laptop is new and provided by Dell.
It does not crash in Debug mode though.
I have disabled Windows Defender, Firewall etc.

The same program, with the same environment on a Windows 8.1 Pro 64 Bits virtual machine works perfectly.

Whether there is something wicked in Qt 5.5 or there is something in the Windows 8.1 Pro that disturbs Qt lib (security setting?).

I'll try to recompile Qt tomorrow in order to put some trace instructions and find out where it crashes.

K.