threads won't finish when reading data from file

Hey,
i got some problems here, but cannot find any answer (googled for a while now)

I'm doing some parallel calculation with QFutureWatcher. Basically it works fine, but if I fetch some global parameters from a file before I start the calculation, the threads of the watcher won't finish anymore.
at the moment I use QSettings to read the file, but it also happened with QFile.
If I remove the code which reads the file it everything works fine.

Am I missing something?

The Code to read the file:

Code:

---

QString fileName=QFileDialog::getOpenFileName(this,tr("load magnets ..."),QDir::homePath(),tr("File (*.ini)"));
    if(fileName.length()>0) {
        QSettings *settings = new QSettings(fileName,QSettings::IniFormat);
        QStringList list_of_magnets = settings->childGroups();
        foreach (QString magnet, list_of_magnets) {
            settings->beginGroup(magnet);
            addMagnet( ... );
            settings->endGroup();
        }
        delete settings;
    }

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Step through and see if it hangs on a call (as in dead lock) or loops somewhere for ever...