Maemo 5: All Qt applications segfault when launched while a portrait-mode application is on the screen

If I launch any Qt application on the Nokia N900's Maemo 5 while a portrait-mode application is visible on the screen, the application just segfaults. I've noticed that the segfault happens when I instantiate a QApplication object, in which case any Qt application unconditionally throws a segfault when trying to launch it with a portrait-mode app (eg. phone application, or any other portrait-supporting app) on the screen.

The bug is further described on:
http://talk.maemo.org/showpost.php?p=905622&postcount=14