I had a hard time today figuring out why Qt 4.4 issues a

QObject: Do not delete object, 'unnamed'

during its event handler. In my code. I ended up patching qobject.cpp to get some more information
on the object. So here is my suggestion. At the end of QObject::~QObject you currently have:

    if (d->inEventHandler) {
        qWarning("QObject: Do not delete object, '%s', during its event handler!",
        objectName().isNull() ? "unnamed" : qPrintable(objectName()));
    }

I would suggest to move this to the beginning of the destructor (because
here the internals are not yet cleaned up) and add a dumpObjectInfo(); so that this looks like that:

    QObject::~QObject()
    {
        Q_D(QObject);
        if (d->wasDeleted) {
            #if defined(QT_DEBUG)
                qWarning("QObject: Double deletion detected");
            #endif
            return;
    }
    
    if (d->inEventHandler) {
        qWarning("QObject: Do not delete object, '%s', during its event handler!",
            objectName().isNull() ? "unnamed" : qPrintable(objectName()));
        this->dumpObjectInfo();
    }

This would make finding the culprit in these cases much easier, because
you get information on connected signals etc. Of course you should additionally check if debug output is desired.