1. in one qt-application doing
QDrag *drag = new QDrag(this);
QMimeData *mimeData = new QMimeData;
mimeData->setUrls(QList<QUrl>());
drag->setMimeData(mimeData);
drag->exec();
2. in another qt-application calling "event->mimeData()->urls()" on a drag-event
-> the first application will crash

... this wont happen if the 2nd application is a non-qt-app (e.g. dragging to SciTE-tab-bar)
... this wont happen if the drag&drop is in the same application!

first found this in my commercial(still using qt4.5.1 with mingw-gcc3.4) ...
... this bug still exists with latest SDK (qt4.6.2 ... using WindowsVista)

I build a little test application ... attached as a zip ... you have to start to instances of this application and drag from one to the otherone ...

... first found this issue when accidentally dragging a "bad"-drag from my app across a qtcreator (result: creator was crashing my app ^^)