Windows: QSplashScreen image display regression

When migrated to Qt5 the png image of the splash screen began to appear strange. When Aero is enabled white pixels appears on some edges in the PNG. There is no problems with the drop shadow, buth with some edges in the image. When Aero is off the edges are even uglier. Also some text antializing can be noticed on the message box but probably this is for another thread. This sample code reproduces the problem with the QSplashScreen image.

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

QSplashScreen splash(QPixmap(":/img/res/ss256.png"), Qt::SplashScreen | Qt::WindowStaysOnTopHint);

splash.show();

MainWindow w;
splash.finish(&w);

QTimer::singleShot(3000, &w, SLOT(show()));

return a.exec();
}

The following image sample display the splash screen in the version sequence:
1. Qt 4.8.4 - Aero on
2. Qt 5.0.2 - Aero on
3. Qt 5.0.2 - Aero off

Tried with VS2010 and mingw build. The result is the same.
When converted the same PNG to TIF the issue does not appear.
When compiled Qt5 with VS2008 and builded the project with VS2008 the issue does not appear.
configure -developer-build -opensource -nomake examples -nomake tests -mp -confirm-license -opengl desktop -no-icu