When changing fonts from system to a user selected font and then pressing apply kmymoney crashes with an access violation

The violation occurs in the following code in qtgui.dll

qwidget.cpp Line 2709

QStyle *QWidget::style() const
{
    Q_D(const QWidget);

    if (d->extra && d->extra->style) <== access violation here
        return d->extra->style;
    return QApplication::style();
}