QPrinter/QPrintDialog pointer error

from PyQt4.QtGui import QApplication, QPrinter, QPrintDialog, QLabel, QPainter, QDialog
import sys

if name == '_main_':
app = QApplication(sys.argv)

printer = QPrinter()
printDialog = QPrintDialog(printer, None)
printDialog.setWindowTitle("Print page");
if (printDialog.exec_() == QDialog.Accepted):
printLabel = QLabel("Hello printer!")
painter = QPainter()
painter.begin(printer)
printLabel.render(painter)
painter.end()

sys.exit(app.exec_())

We get the following error:
Python(817,0xa066a720) malloc: *** error for object 0xcd0200: pointer being freed was not allocated