1) Find the file "boot_common.py" in your py2exe module (exemple: c:\python2x\Lib\site-packages\py2exe\boot_common.py) and make a backup copy in case of.
2) find the "def write" method and add a show_dialog parmeter this way:
def write(self, text, alert=sys._MessageBox, fname=sys.executable + '.log', show_dialog=False):
3) modify the following "else" block this way:
if show_dialog==True:
import atexit
atexit.register(alert, 0,"See the logfile '%s' for details" % fname,"Errors occurred")
else:
pass
To come back to the original behavior change to "show_dialog=True" in 2).
More informations on Py2exe error handling here.