Did you get any messages from Qt (apart from that assert statement) while the app was running?
No, I dont get any other messages while the app is running.

Did you compile Qt yourself or do you have it from a binary distribution?
Yes, I did compile QT myself.

Was it compiled using the same compiler?
Yes

Are you using a stable version of Qt (the one which was released today) or a daily snapshot?
I am using a daily snapshot : qt-x11-opensource-src-4.1.1-snapshot-20060221