QFileDialog hang ups

I was trying to use QFileDialog::getOpenFileName static function,when i ran my app normally not in debugging mode it runs fine, but when i ran it in my debugger (GDB) i encountered some "segmentation fault"

please see my code below

Code:

void MyFunc::openCFGFile(void)
{
    QString strFile = QFileDialog::getOpenFileName(this,
                      tr("Select Configuration File To Open"),"",
                      "Configuration File (*.cfg)"); // <--segmentation fault happen here
    if (strFile.isEmpty())
        return;
    //store cfgFile
    cfgFile = new QFile(strFile);
    if (!cfgFile->open(QFile::ReadOnly))
    {
        QMessageBox::warning(this, tr("File Open Error"),
                             tr("Cannot Open file %1:\n%2.")
                             .arg(strFile)
                             .arg(cfgFile->errorString()));
        cfgFile->close();
        return;
    }
    cfgFile->close();
}

please tell me what did i do wrong?

baray98