I'm somewhat confused. Your comment suggests that the QT version was the correct one, then.
I worry that your problems may not be over. For instance, if you have an intermittent display cable, simply fiddling with your computer could've fixed things for a time, with none of it due to QT. If the problem should recur, you may want to take a look at the cable (a known source of problems similar to the one you originally reported).